Schlumberger
Log
Interpretation
Charts
2009 Edition
Intro < ► Contents
Schlumberger
225 Schlumberger Drive
Sugar Land, Texas 77478
www.slb.com
© 2009 Schlumberger. All rights reserved.
No part of this book may be reproduced, stored
in a retrieval system, or transcribed in any
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including photocopying and recording, without
the prior written permission of the publisher.
While the information presented herein is
believed to be accurate, it is provided "as is"
without express or implied warranty.
Specifications are current at the time of printing.
09-FE-0058
An asterisk (*) is used throughout this document to
denote a mark of Schlumberger.
Intro < ► Contents
Intro < ► Contents
Contents
Schlumberger
Contents
Foreword xi
General
Symbols Used in Log Interpretation Gen-1 1
Estimation of Formation Temperature with Depth Gen-2 3
Estimation of R in f and R mc Gen-3 4
Equivalent NaCl Salinity of Salts Gen-4 5
Concentration of NaCl Solutions Gen-5 6
Resistivity of NaCl Water Solutions Gen-6 8
Density of Water and Hydrogen Index of Water and Hydrocarbons Gen-7 9
Density and Hydrogen Index of Natural Gas Gen-8 10
Sound Velocity of Hydrocarbons Gen-9 11
Gas Effect on Compressional Slowness Gen-9a 12
Gas Effect on Acoustic Velocity Gen-9b 13
Nuclear Magnetic Resonance Relaxation Times of Water Gen- 10 14
Nuclear Magnetic Resonance Relaxation Times of Hydrocarbons Gen-lla 15
Nuclear Magnetic Resonance Relaxation Times of Hydrocarbons Gen-llb 16
Capture Cross Section of NaCl Water Solutions Gen-12 18
Capture Cross Section of NaCl Water Solutions Gen-13 19
Capture Cross Section of Hydrocarbons Gen- 14 21
EPT* Propagation Time of NaCl Water Solutions Gen-15 22
EPT Attenuation of NaCl Water Solutions Gen-16 23
EPT Propagation Time -Attenuation Crossplot Gen-16a 24
Gamma Ray
Scintillation Gamma Ray — 3%- and 1%-in. Tools GR-1 25
Scintillation Gamma Ray — 3%- and 1%-in. Tools GR-2 26
Scintillation Gamma Ray— 3%- and 1%-in. Tools GR-3 27
StimPulse* and E-Pulse* Gamma Ray Tools GR-6 28
ImPulse* Gamma Ray— 4.75-in. Tool GR-7 29
PowerPulse* and TeleScope* Gamma Ray— 6.75-in. Tools GR-9 30
PowerPulse Gamma Ray— 8.25-in. Normal-Flow Tool GR-10 31
PowerPulse Gamma Ray— 8.25-in. High-Flow Tool GR-11 32
PowerPulse Gamma Ray— 9-in. Tool GR-12 33
PowerPulse Gamma Ray — 9.5-in. Normal-Flow Tool GR-13 34
PowerPulse Gamma Ray — 9.5-in. High-Flow Tool GR-14 35
geoVISION675* GVR* Gamma Ray— 6.75-in. Tool GR-15 36
RAB* Gamma Ray— 8.25-in. Tool GR-16 37
arcVISION475* Gamma Ray— 4.75-in. Tool GR-19 38
Intro
Contents
Schlumberger
arcVISION675* Gamma Ray— 6.75-in. Tool GR-20 39
arcVISION825* Gamma Ray— 8.25-in. Tool GR-21 40
arcVISION900* Gamma Ray— 9-in. Tool GR-22 41
arcVISION475 Gamma Ray— 4.75-in. Tool GR-23 42
arcVISION675 Gamma Ray— 6.75-in. Tool GR-24 43
arcVISION825 Gamma Ray— 8.25-in. Tool GR-25 44
arcVISION900 Gamma Ray— 9-in. Tool GR-26 45
EcoScope* Integrated LWD Gamma Ray— 6.75-in. Tool GR-27 46
EcoScope Integrated LWD Gamma Ray— 6.75-in. Tool GR-28 47
Spontaneous Potential
Rweq Determination from Essp SP-1 49
Rweq versus R w and Formation Temperature SP-2 50
Rweq versus R w and Formation Temperature SP-3 51
Bed Thickness Correction — Open Hole SP-4 53
Bed Thickness Correction — Open Hole (Empirical) SP-5 54
Bed Thickness Correction — Open Hole (Empirical) SP-6 55
Density
Porosity Effect on Photoelectric Cross Section Dens-1 56
Apparent Log Density to True Bulk Density Dens-2 57
Neutron
Dual-Spacing Compensated Neutron Tool Charts 58
Compensated Neutron Tool Neu-1 60
Compensated Neutron Tool Neu-2 61
Compensated Neutron Tool Neu-3 63
Compensated Neutron Tool Neu-4 64
Compensated Neutron Tool Neu-5 65
Compensated Neutron Tool Neu-6 67
Compensated Neutron Tool Neu-7 69
Compensated Neutron Tool Neu-8 71
Compensated Neutron Tool Neu-9 73
APS* Accelerator Porosity Sonde Neu-10 75
APS Accelerator Porosity Sonde Without Environmental Corrections Neu-11 76
CDN* Compensated Density Neutron, adnVISION* Azimuthal Density
Neutron, and EcoScope* Integrated LWD Tools Neu-30 78
adnVISION475* Azimuthal Density Neutron— 4.75-in. Tool and 6-in. Borehole Neu-31 80
adnVISION475 BIP Neutron— 4.75-in. Tool and 6-in. Borehole Neu-32 81
adnVISION475 Azimuthal Density Neutron— 4.75-in. Tool and 8-in. Borehole Neu-33 82
adnVISION475 BIP Neutron— 4.75-in. Tool and 8-in. Borehole Neu-34 83
Intro
Contents
Schlumberger
adnVISION675* Azimuthal Density Neutron— 6. 75-in. Tool and 8-in. Borehole Neu-35 .
adnVISION675 BIP Neutron— 6. 75-in. Tool and 8-in. Borehole Neu-36 .
adnVISION675 Azimuthal Density Neutron— 6. 75-in. Tool and 10-in. Borehole Neu-37 .
adnVISION675 BIP Neutron— 6. 75-in. Tool and 10-in. Borehole Neu-38 .
adnVISION825* Azimuthal Density Neutron— 8.25-in. Tool and 12.25-in. Borehole Neu-39 .
CDN Compensated Density Neutron and adnVISION825s* Azimuthal Density Neutron —
8-in. Tool and 12-in. Borehole Neu-40 .
CDN Compensated Density Neutron and adnVISION825s Azimuthal Density Neutron —
8-in. Tool and 14-in. Borehole Neu-41 .
CDN Compensated Density Neutron and adnVISION825s Azimuthal Density Neutron —
8-in. Tool and 16-in. Borehole Neu-42 .
EcoScope* Integrated LWD BPHI Porosity— 6. 75-in. Tool and 8.5-in. Borehole Neu-43 .
EcoScope Integrated LWD BPHI Porosity— 6. 75-in. Tool and 9.5-in. Borehole Neu-44 .
EcoScope Integrated LWD TNPH Porosity— 6. 75-in. Tool and 8.5-in. Borehole Neu-45 .
EcoScope Integrated LWD TNPH Porosity— 6. 75-in. Tool and 9.5-in. Borehole Neu-46 .
EcoScope Integrated LWD— 6. 75-in. Tool Neu-47 .
Nuclear Magnetic Resonance
CMR* Tool CMR-1. .
.84
.85
.86
.87
.91
.94
Resistivity Laterolog
ARI* Azimuthal Resistivity Imager RL1-1 . .
High-Resolution Azimuthal Laterolog Sonde (HALS) RL1-2 . .
High-Resolution Azimuthal Laterolog Sonde (HALS) RL1-3 . .
High-Resolution Azimuthal Laterolog Sonde (HALS) RL1-4 . .
High-Resolution Azimuthal Laterolog Sonde (HALS) RL1-5 . .
High-Resolution Azimuthal Laterolog Sonde (HALS) RL1-6 . .
High-Resolution Azimuthal Laterolog Sonde (HALS) RL1-7 . .
High-Resolution Azimuthal Laterolog Sonde (HALS) RL1-8 . .
High-Resolution Azimuthal Laterolog Sonde (HALS) RL1-9 . .
HRLA* High-Resolution Laterolog Array RL1-10.
.101
.102
.103
.104
.105
.106
.107
.108
.109
.110
HRLA High-Resolution Laterolog Array RL1-11 Ill
HRLA High-Resolution Laterolog Array RL1-12 112
HRLA High-Resolution Laterolog Array RL1-13 113
HRLA High-Resolution Laterolog Array RL1-14 114
GeoSteering* Bit Resistivity— 6. 75-in. Tool RL1-20 115
GeoSteeringarcVISION675 Resistivity— 6. 75-in. Tool RL1-21 116
GeoSteering Bit Resistivity in Reaming Mode— 6. 75-in. Tool RL1-22 117
geoVISION* Resistivity Sub— 6. 75-in. Tool RL1-23 118
geoVISION Resistivity Sub— 8.25-in. Tool RL1-24 119
GeoSteering Bit Resistivity— 6. 75-in. Tool RL1-25 120
Intro
Contents
Schlumberger
CHFR* Cased Hole Formation Resistivity Tool RL1-50 121
CHFR Cased Hole Formation Resistivity Tool RL1-51 122
CHFR Cased Hole Formation Resistivity Tool RL1-52 123
Resistivity Induction
AIT* Array Induction Imager Tool RInd-1 125
AIT Array Induction Imager Tool 126
Resistivity Electromagnetic
arcVISION475 and ImPulse 4 3 /4-in. Array Resistivity Compensated Tools— 2 MHz REm-11 131
arcVISION475 and ImPulse 4 3 /4-in. Array Resistivity Compensated Tools— 2 MHz REm-12 132
arcVISION475 and ImPulse 4 3 /4-in. Array Resistivity Compensated Tools— 2 MHz REm-13 133
arcVISION475 and ImPulse 4 3 /4-in. Array Resistivity Compensated Tools — 2 MHz REm-14 134
arcVISION675 6 3 /4-in. Array Resistivity Compensated Tool— 400 kHz REm-15 135
arcVISION675 6 3 /4-in. Array Resistivity Compensated Tool— 400 kHz REm-16 136
arcVISION675 6 3 /4-in. Array Resistivity Compensated Tool— 400 kHz REm-17 137
arcVISION675 6 3 /4-in. Array Resistivity Compensated Tool— 400 kHz REm-18 138
arcVISION675 6 3 /4-in. Array Resistivity Compensated Tool— 2 MHz REm-19 139
arcVISION675 6^-in. Array Resistivity Compensated Tool— 2 MHz REm-20 140
arcVISION675 6%-in. Array Resistivity Compensated Tool— 2 MHz REm-21 141
arcVISION675 6M-in. Array Resistivity Compensated Tool— 2 MHz REm-22 142
arcVISION825 8K-in. Array Resistivity Compensated Tool— 400 kHz REm-23 143
arcVISION825 8K-in. Array Resistivity Compensated Tool— 400 kHz REm-24 144
arcVISION825 8%-in. Array Resistivity Compensated Tool— 400 kHz REm-25 145
arcVISION825 8K-in. Array Resistivity Compensated Tool— 400 kHz REm-26 146
arcVISION825 8K-in. Array Resistivity Compensated Tool— 2 MHz REm-27 147
arcVISION825 8%-in. Array Resistivity Compensated Tool— 2 MHz REm-28 148
arcVISION825 M-in. Array Resistivity Compensated Tool— 2 MHz REm-29 149
arcVISION825 8K-in. Array Resistivity Compensated Tool— 2 MHz REm-30 150
arcVISION900 9-in. Array Resistivity Compensated Tool— 400 kHz REm-31 151
arcVISION900 9-in. Array Resistivity Compensated Tool— 400 kHz REm-32 152
arcVISION900 9-in. Array Resistivity Compensated Tool— 400 kHz REm-33 153
arcVISION900 9-in. Array Resistivity Compensated Tool— 400 kHz REm-34 154
arcVISION900 9-in. Array Resistivity Compensated Tool— 2 MHz REm-35 155
arcVISION900 9-in. Array Resistivity Compensated Tool— 2 MHz REm-36 156
arcVISION900 9-in. Array Resistivity Compensated Tool— 2 MHz REm-37 157
Intro
Contents
Schlumberger
arcVISION900 9-in. Array Resistivity Compensated Tool— 2 MHz REm-38 158
arcVISION675, arcVISION825, and arcVISION900 Array Resistivity Compensated Tools— 400 kHz REm-55 160
arcVISION and ImPulse Array Resistivity Compensated Tools — 2 MHz REm-56 161
arcVISION675 and ImPulse Array Resistivity Compensated Tools — 2 MHz and 16-in. Spacing REm-58 162
arcVISION675 and ImPulse Array Resistivity Compensated Tools — 2 MHz and 22-in. Spacing REm-59 163
arcVISION675 and ImPulse Array Resistivity Compensated Tools — 2 MHz and 28-in. Spacing REm-60 164
arcVISION675 and ImPulse Array Resistivity Compensated Tools — 2 MHz and 34-in. Spacing REm-61 165
arcVISION675 and ImPulse Array Resistivity Compensated Tools — 2 MHz and 40-in. Spacing REm-62 166
arcVISION675 and ImPulse Array Resistivity Compensated Tools — 2 MHz with Dielectric Assumption REm-63 167
Formation Resistivity
Resistivity Galvanic Rt-1 168
High-Resolution Azimuthal Laterlog Sonde (HALS) Rt-2 169
High-Resolution Azimuthal Laterlog Sonde (HALS) Rt-3 170
geoVISION675* Resistivity Rt-10 171
geoVISION675 Resistivity Rt-11 172
geoVISION675 Resistivity Rt-12 173
geoVISION675 Resistivity Rt-13 174
geoVISION825* 8^-in. Resistivity-at-the-Bit Tool Rt-14 175
geoVISION825 8X-in. Resistivity-at-the-Bit Tool Rt-15 176
geoVISION825 8X-in. Resistivity-at-the-Bit Tool Rt-16 177
geoVISION825 8 l A-m. Resistivity-at-the-Bit Tool Rt-17 178
arcVISION Array Resistivity Compensated Tool— 400 kHz Rt-31 179
arcVISION and ImPulse Array Resistivity Compensated Tools— 2 MHz Rt-32 180
arcVISION Array Resistivity Compensated Tool— 400 kHz Rt-33 181
arcVISION and ImPulse Array Resistivity Compensated Tools— 2 MHz Rt-34 182
arcVISION Array Resistivity Compensated Tool— 400 kHz Rt-35 183
arcVISION and ImPulse Array Resistivity Compensated Tools— 2 MHz Rt-36 184
arcVISION675 Array Resistivity Compensated Tool— 400 kHz Rt-37 185
arcVISION675 and ImPulse Array Resistivity Compensated Tools— 2 MHz Rt-38 186
arcVISION Array Resistivity Compensated Tool— 400 kHz Rt-39 187
arcVISION and ImPulse Array Resistivity Compensated Tools— 2 MHz Rt-40 188
arcVISION Array Resistivity Compensated Tool— 400 kHz in Horizontal Well Rt-41 190
arcVISION and ImPulse Array Resistivity Compensated Tools — 2 MHz in Horizontal Well Rt-42 191
Intro
Contents
Schlumberger
Lithology
Density and NGS* Natural Gamma Ray Spectrometry Tool Lith-1 193
NGS Natural Gamma Ray Spectrometry Tool Lith-2 194
Platform Express* Three-Detector Lithology Density Tool Lith-3 196
Platform Express Three-Detector Lithology Density Tool Lith-4 197
Density Tool Lith-5 198
Density Tool Lith-6 200
Environmentally Corrected Neutron Curves Lith-7 202
Environmentally Corrected APS Curves Lith-8 204
Bulk Density or Interval Transit Time and Apparent Total Porosity Lith-9 206
Bulk Density or Interval Transit Time and Apparent Total Porosity Lith-10 207
Density Tool Lith-11 209
Density Tool Lith-12 210
Porosity
Sonic Tool Por-1 212
Sonic Tool Por-2 213
Density Tool Por-3 214
APS Near-to-Array (APLC) and Near-to-Far (FPLC) Logs Por-4 216
Thermal Neutron Tool Por-5 217
Thermal Neutron Tool— CNT-D and CNT-S 2^-in. Tools Por-6 218
adnVISION475 4.75-in. Azimuthal Density Neutron Tool Por-7 219
adnVISION675 6.75-in. Azimuthal Density Neutron Tool Por-8 220
adnVISION825 8.25-in. Azimuthal Density Neutron Tool Por-9 221
EcoScope* 6.75-in. Integrated LWD Tool, BPHI Porosity Por-10 222
EcoScope 6.75-in. Integrated LWD Tool, TNPH Porosity Por-lOa 223
CNL* Compensated Neutron Log and Litho-Density* Tool (fresh water in invaded zone) Por-11 225
CNL Compensated Neutron Log and Litho-Density Tool (salt water in invaded zone) Por-12 226
APS and Litho-Density Tools Por-13 227
APS and Litho-Density Tools (saltwater formation) Por-14 228
adnVISION475 4.75-in. Azimuthal Density Neutron Tool Por-15 229
adnVISION675 6.75-in. Azimuthal Density Neutron Tool Por-16 230
adnVISION825 8.25-in. Azimuthal Density Neutron Tool Por-17 231
EcoScope 6.75-in. Integrated LWD Tool Por-18 232
EcoScope 6.75-in. Integrated LWD Tool Por-19 233
Sonic and Thermal Neutron Crossplot Por-20 235
Sonic and Thermal Neutron Crossplot Por-21 236
Density and Sonic Crossplot Por-22 238
Density and Sonic Crossplot Por-23 239
Density and Neutron Tool Por-24 241
Intro
Contents
Schlumberger
Density and APS Epithermal Neutron Tool Por-25.
Density, Neutron, and R xo Logs Por-26.
Hydrocarbon Density Estimation Por-27.
Saturation
Porosity Versus Formation Resistivity Factor SatOH-1.
Spherical and Fracture Porosity SatOH-2.
Saturation Determination SatOH-3.
Saturation Determination SatOH-4.
Graphical Determination of Sw from Swt and Swb SatOH-5.
Porosity and Gas Saturation in Empty Hole SatOH-6.
EPT Propagation Time SatOH-7.
EPT Attenuation SatOH-8.
Capture Cross Section Tool SatCH-1.
Capture Cross Section Tool SatCH-2.
.243
.245
.246
.247
.248
.250
.252
.253
.254
.255
.256
.258
.260
RST* Reservoir Saturation Tool— 1.6875 in. and 2.5 in 261
RST Reservoir Saturation Tool— 1.6875 in. and 2.5 in. in 6.125-in. Borehole SatCH-3 262
RST Reservoir Saturation Tool— 1.6875 in. and 2.5 in. in 9.875-in. Borehole SatCH-4 263
RST Reservoir Saturation Tool— 1.6875 in. and 2.5 in. in 8.125-in. Borehole with 4.5-in. Casing at 11.6 lbm/ft .... SatCH-5 264
RST Reservoir Saturation Tool— 1.6875 in. and 2.5 in. in 7.875-in. Borehole with 5.5-in. Casing at 17 lbm/ft SatCH-6 265
RST Reservoir Saturation Tool— 1.6875 in. and 2.5 in. in 8.5-in. Borehole with 7-in. Casing at 29 lbm/ft SatCH-7 266
RST Reservoir Saturation Tool— 1.6875 in. and 2.5 in. in 9.875-in. Borehole with 7-in. Casing at 29 lbm/ft SatCH-8 267
Permeability
Permeability from Porosity and Water Saturation Perm-1 269
Permeability from Porosity and Water Saturation Perm-2 270
Fluid Mobility Effect on Stoneley Slowness Perm-3 271
Cement Evaluation
Cement Bond Log — Casing Strength.
.Cem-1 274
Appendixes
Appendix A
Appendix B
Appendix C
Appendix D
Appendix E
Appendix F
Appendix G
Appendix H
Linear Grid 275
Log-Linear Grid 276
Water Saturation Grid for Resistivity Versus Porosity 277
Logging Tool Response in Sedimentary Minerals 279
Acoustic Characteristics of Common Formations and Fluids 281
Conversions 282
Symbols 285
Subscripts 287
Unit Abbreviations 290
References 292
Intro
Intro < ► Contents
Foreword
Foreword
Schlumberger
This edition of the Schlumberger "chartbook" presents several
innovations.
First, the charts were developed to achieve two purposes:
■ Correct raw measurements to account for environmental effects
Early downhole measurements were performed in rather uniform
conditions (vertical wells drilled through quasi-horizontal thick
beds, muds made of water with a narrow selection of additives,
and limited range of hole sizes), but today wells can be highly
deviated or horizontal, mud contents are diverse, and hole sizes
range from 2 to 40 in. Environmental effects may be large. In
addition, they compound. It is essential to correct for these effects
before the measurements are used.
■ Use environmentally corrected measurements for interpretation
Charts related to measurements that are no longer performed
are not included in this chartbook. However, because many oil and
gas companies use logs acquired years or even decades ago, the
second chartbook, Historical Log Interpretation, Charts, contains
these old charts.
Why publish charts on paper in our electronic age? It is true that
software may be more effective than pencil to derive results. Even
more so, this chartbook cannot cope with the complex well situations
that are encountered. Using software is the only way to proceed.
Thus, the chartbook has two primary functions:
■ Training
The chartbook is essential for educating junior petrophysicists
about the different effects on the measurements. In the interpre-
tation process, the chartbook unveils the relationships between
the different parameters.
■ Sensitivity analysis
A chart gives the user a graphical idea of the sensitivity of an out-
put to the various inputs (see Chart Gen-1). The visual presenta-
tion is helpful for determining if an input parameter is critical.
The user can then focus on the most sensitive inputs.
Back to Contents
-4 ►
Back to Contents
General
Symbols Used in Log Interpretation
Schlumberger
Gen-1
(former Gen-3)
] Resistivity of the zone
O Resistivity of the water in the zone
/\ Water saturation in the zone
Mud
Adjacent bed
Adjacent bed
Invasion diameters)
© Schlumberger
Purpose
This diagram presents the symbols and their descriptions and rela-
tions as used in the charts. See Appendixes D and E for identifica-
tion of the symbols.
Description
The wellbore is shown traversing adjacent beds above and below the
zone of interest. The symbols and descriptions provide a graphical
representation of the location of the various symbols within the well-
bore and formations.
< ►
Back to Contents
General
Schlumberger
Estimation of Formation Temperature with Depth
Purpose
This chart has a twofold purpose. First, a geothermal gradient can
be assumed by entering the depth and a recorded temperature at
that depth. Second, for an assumed geothermal gradient, if the tem-
perature is known at one depth in the well, the temperature at
another depth in the well can be determined.
Description
Depth is on the y-axis and has the shallowest at the top and the
deepest at the bottom. Both feet and meters are used, on the left
and right axes, respectively. Temperature is plotted on the x-axis,
with Fahrenheit on the bottom and Celsius on the top of the chart.
The annual mean surface temperature is also presented in
Fahrenheit and Celsius.
Example
Given:
Find:
Answer:
Bottomhole depth = 11,000 ft and bottomhole tempera-
ture = 200°F (annual mean surface temperature = 80°F).
Temperature at 8,000 ft.
The intersection of 11,000 ft on the y-axis and 200°F
on the x-axis is a geothermal gradient of approximately
1.1°F/100 ft (Point A on the chart).
Move upward along an imaginary line parallel to the con-
structed gradient lines until the depth line for 8,000 ft is
intersected. This is Point B, for which the temperature
on the x-axis is approximately 167°F.
Back to Contents
General
Estimation of Formation Temperature with Depth
Schlumberger
Gen -2
(former Gen-6)
Temperature gradient conversions: 1°F/100ft= 1.823°C/100m
rC/100m=0.5486°F/100ft
Annual mean
surface temperature x ,.„,
I r Temperature (°C)
27 50 75 100 125 150 175
16 ^25
50
75
100
125
150
175
: 1
i 2
L 3
: 4
Depth
(thousands
: p. of meters)
5
10
Depth
(thousands 15
of feet)
20
25
A
X ^1^
\
v >
s>
> \
\
\
s
s
V
\
N
>
N
>
s,
B^
\
V
v
\
^S
s
*v
0.6 0.8
1.0 s
V 1.2
1.4 1.6°F/100fl
Geothermal aradient
\
\
\
\
\
N.
\
v
\
\
\
A
\
N
\
\
V
^
<
s
\
Ss
1.09
1.46
1.82
2.19
2.55
2.92°C/100m
\
N
V
s
\
\
V
t
>
\
>
^
V
V
\
s
V
V
\
s
k.
•
i 6
: 7
N
N
\
\
\
\
v
>
s
>
s
\
N
s
i 8
\
N
1
\
\
k
\
\
\
\
8
3
100
150
200
250
300
350
6
An
su
© Schlumberger
3 100 150 200 250 300 350
, Temperature (°F)
nual mean
rface temperature
< ►
Back to Contents
General
Estimation of R m f and R mc
Fluid Properties
Schlumberger
Gen -3
(former Gen-7)
Purpose
Direct measurements of nitrate and mudcake samples are preferred.
When these are not available, the mud filtrate resistivity (Rmf) and
mudcake resistivity (R m c) can be estimated with the following
methods.
Description
Method 1: Lowe and Dunlap
For freshwater muds with measured values of mud resistivity (R m )
between 0.1 and 2.0 ohm-m at 75°F [24°C] and measured values of
mud density (p m ) (also called mud weight) in pounds per gallon:
log
R
mf
V R my
: 0.396- (0.0475 xp m ).
Method 2: Overton and Upson
For drilling muds with measured values of R m between 0. 1 and
10.0 ohm-m at 75°F [24°C] and the coefficient of mud (K m ) given
as a function of mud weight from the table:
Mud Weight
Ibm/gal
kg/m 3
Km
10
1,200
0.847
11
1,320
0.708
12
1,440
0.584
13
1,560
0.488
14
1,680
0.412
16
1,920
0.380
18
2,160
0.350
Example
Given:
Find:
Answer:
R m = 3.5 ohm-m at 75°F and mud weight = 12 lbm/gal
[1,440 kg/m 3 ].
Estimated values of R in f and R mc .
From the table, K m = 0.584.
Rmt = (0.584) (3.5) 107 = 2.23 ohm-m at 75°F.
R mc = 0.69(2.23) (3.5/2.23) 2 65 = 5.07 ohm-m at 75°F.
R mf = K m (R m )
R mc = 0.69(R mf )
1.07
/ n2.65
v R mfy
Back to Contents
General
Equivalent NaCI Salinity of Salts
Schlumberger
Gen -4
(former Gen-8)
2.0
A
Li(2.5) f OH 5.5) f
2.0
1.5
1.0
Multiplier
0.5
-0.5
I T-—
1.0
NH
,U-
ir
„Mq
A
Ca
nn-
-Na;
mrl
m
1 (
i) --
K
!^c Ca
" so,
■-^co 3
- NCMO^)'
- Br(0.44) f
HC(
v
Qfl
i (n ">Qit
urn
— 1 (U.
3
Mg\
1
© Schlumberger
20 50 100 200 500 1,000 2,000 5,000 10,000 20,000 50,000 100,000 300,000
Total solids concentration (ppm or mg/kg)
' Multipliers that do not vary appreciably for low concentrations
(less than about 10,000 ppml are shown at the left margin of the chart
Purpose Example
This chart is used to approximate the parts-per-million (ppm) con- Given:
centration of a sodium chloride (NaCI) solution for which the total
solids concentration of the solution is known. Once the equivalent
concentration of the solution is known, the resistivity of the solution
for a given temperature can be estimated with Chart Gen-6. p m( j.
Description Answer:
The x-axis of the semilog chart is scaled in total solids concentration
and the y-axis is the weighting multiplier. The curve set represents
the various multipliers for the solids typically in formation water.
Formation water sample with solids concentrations
of calcium (Ca) = 460 ppm, sulfate (SO4) = 1,400 ppm,
and Na plus CI = 19,000 ppm. Total solids concentration
= 460 + 1,400 + 19,000 = 20,860 ppm.
Equivalent NaCI solution in ppm.
Enter the x-axis at 20,860 ppm and read the multiplier
value for each of the solids curves from the y-axis:
Ca = 0.81, S0 4 = 0.45, and NaCI = 1.0. Multiply each
concentration by its multiplier:
(460 x 0.81) + (1,400 x 0.45) + (19,000 x 1.0) = 20,000 ppm.
Back to Contents
General
Concentration of NaCI Solutions
Schlumberger
Gen -5
Concentrations of NaCI Solutions
Temperature Gradient
Oil Gravity
Density of NaCI
Conversion
g/Lat ppm grains/gal solution at
Specific
77°F at77°F 77°F[25°C]
°F/100ft °C/100ft
°API gravity (sg) at 60°F
0.15 150 _,
1.00
2.0
0.60
0.2 .
200 .
. 10
. 12.5
. 15
1.9 :
. 3.5
100 :
. 0.62
0.3 .
300 .
. 20
90 :
. 0.64
0.4 1
. 400 i
. 25
1.8 :
. 0.66
0.5 i
'. 500 :
. 30
so :
. 0.68
0.6 :
i 600 :
1.7 :
. 40
70 1
. 0.70
0.8 -
. 800 ~
. 50
. 3.0
. 0.72
1.0 :
: 1,000 :
. 60
1.6 :
. 70
60 :
. 0.74
. 80
1.5 :
'. 1,500 J
-90
1.5 :
. 0.76
- 100
50 :
. 0.78
2 1
L 2,000 1
- 125
. 0.80
3 .
. 3,000 .
. 150
. 200
1.4 :
. 2.5
40 :
. 0.82
. 0.84
4 i
'. 4,000 1
. 250
1.3 :
.
30 :
. 0.86
. 0.88
5 1
'. 5,000 1
.300
6 .
. 6,000 .
. 400
. 1.005
1.2 :
20 :
. 0.90
. 0.92
8 i
'. 8,000 I
. 500
. 0.94
. 0.96
10 1
L 10,000 I
.600
1.1 :
. 2.0
- 0.98
. 700
10 :
. 1.00
800
.
■
. 1.02
15 :
1 15,000 :
. 900
1.0 1
. 1.04
20 j
L 20,000 1
- 1,000
. 1,250
. 1.01
o :
. 1.06
C 1.08
- 1,500
0.9 :
30 .
. 30,000 .
141 5
°API - 131 5
. 2,000
. 1.02
. 1.5
r\i \ — 1 Jl ,J
sgat60°F
40 .
1 40,000 J
. 2,500
o.8 :
50 :
. 3,000
. 1.03
60 .
i 60,000 :
. 4,000
. 1.04
0.7 :
80 1
- 80,000 '.
. 5,000
. 1.05
100 :
'- 100,000 "
. 6,000
. 1.06
. 1.07
o.6 :
125 .
. 7,000
. 1.08
. 1.0
.822°C/100m
.5488°F/100ft
150 .
200 .
250 .
: 150,000 :
: 200,000 :
. 8,000
- 9,000
- 10,000
. 12,500
. 15,000
. 1.09
. 1.10
. 1.12
. 1.14
. 1.16
1°F/100ft= 1
1°C/100m = C
300 .
- 250,000 .
. 17,500
. 1.18
. 1.20
© Schlumberger
Back to Contents
General
Schlumberger
Resistivity of NaCI Water Solutions
Purpose
This chart has a twofold purpose. The first is to determine the resis-
tivity of an equivalent NaCI concentration (from Chart Gen-4) at a
specific temperature. The second is to provide a transition of resis-
tivity at a specific temperature to another temperature. The solution
resistivity value and temperature at which the value was determined
are used to approximate the NaCI ppm concentration.
Description
The two-cycle log scale on the x-axis presents two temperature
scales for Fahrenheit and Celsius. Resistivity values are on the left
four-cycle log scale y-axis. The NaCI concentration in ppm and
grains/gal at 75°F [24°C] is on the right y-axis. The conversion
approximation equation for the temperature (T) effect on the
resistivity (R) value at the top of the chart is valid only for the
temperature range of 68° to 212°F [20° to 100°C].
Example One
Given: NaCI equivalent concentration = 20,000 ppm.
Temperature of concentration = 75°F
Find: Resistivity of the solution.
Answer: Enter the ppm concentration on the y-axis and the tem-
perature on the x-axis to locate their point of intersec-
tion on the chart. The value of this point on the left
y-axis is 0.3 ohm-m at 75°F.
Example Two
Given: Solution resistivity = 0.3 ohm-m at 75°F.
Find: Solution resistivity at 200°F [93°C].
Answer 1: Enter 0.3 ohm-m and 75°F and find their intersection
on the 20,000-ppm concentration line. Follow the line to
the right to intersect the 200°F vertical line (interpolate
between existing lines if necessary). The resistivity value
for this point on the left y-axis is 0.115 ohm-m.
Answer 2: Resistivity at 200°F = resistivity at 75°F x [(75 + 6.77)/
(200 + 6.77)] = 0.3 x (81.77/206.77) = 0.1186 ohm-m.
< ►
Back to Contents
continued on next page
7
General
Resistivity of NaCI Water Solutions
Schlumberger
Gen -6
(former Gen-9)
Conversion approximated by R 2 = R, [(T, + 6.77)/(T 2 + 6.77)]°F or R 2 = R, [(T, + 21.5)/(T 2 + 21.5)]°C
m
8
6
5
4
3
2
1
0.8
0.6
0.5
0.4
Resistivity
of solution
(ohm-m)
0.2
0.1
0.08
0.06
0.05
0.04
0.03
^■sJ 1 "^.
g
^^r- PPm
■ains/gal
at75°F
?0D
10
115
E. 20
_25
_30
_40
_50
1100
I NaCI
1150 concentration
- onn (ppm ° r
-200 grains/gal)
_ 250
_300
_400
_500
11,000
1 1,500
L 2,000
_ 2,500
_ 3,000
_ 4,000
_ 5,000
110,000
1 15,000
L 20,000
*s^
^
%
^^ %
_^ s — J uo
JX °0q ^^
. ^>Lj j
^*> s % ^--^.
iL " Sn n —
v w ^^^
^^^ "0 — ,
^^\
^r-
^< v '<On ^
Vs., '% ^
<0 0o \
*^J
^^
^ ^>
"^
v fU °o
^tm 4 '°°°
^ * s " s -oo ^
^^" i "- e .o 0o '*s s
"^">^. s ' ^fl/i. ^^
:^->. ' u °o r^
*S^ "Of) >^»
^ ^^ lOn ^^
^, ,'%
'*« - ■ te„ "^.
r^
s^. ^^
^-;- '°0o ^
' N s s ' — ■"^^— -
^^ ^nn \
^-» "°0
^W: "■ /> *" — .
- ^»» 'OOn
====^^
■ ° N
0.02
0.01
IN
■^, *-• <°0n "V
-3<w.
s§: $ ^
r
JCn
„^S». ?o6° n °o
I3S~ ■ ■?"0/)n V
Tr; s - 3f)n "li
°F 5
°C 1
75 1C
D 20 30
i i
125
40 50 E
i i
1
150 200 250 300
70 80 90 100 120 140 16
I 1 %, V.
350 400 <1
D 180 200
i I
© Schlumberger
Temperature
< ►
Back to Contents
General
Schlumberger
Density of Water and Hydrogen Index of Water and Hydrocarbons
Gen -7
Water
density
(g/cm 3 )
Water
Temperature (°C)
25 50 100 150 200
.20 II J J L
Hydrogen
index
40 100
400 440
Temperature (°F)
Pressure 7,000 psi NaCI
1,000 psi
14.7 psi
1.05
Hydrogen Index of Salt Water
1 no
95
nqn
85
50 100 150 200
Salinity (kppm or g/kg)
250
Hydrocarbons
Hydrogen Index of Live Hydrocarbons and Gas
1.2
1.0
0.8
Hydrogen 06
index
0.4
0.2
© Schlumberger
0.2 0.4 0.6 0.8 1.0
Hydrocarbon density (g/cm 3 )
1.2
Purpose
These charts are for determination of the density (g/cm 3 ) and hydro-
gen index of water for known values of temperature, pressure, and
salinity of the water. From a known hydrocarbon density of oil, a
determination of the hydrogen index of the oil can be obtained.
Description: Density of Water
To obtain the density of the water, enter the desired temperature (°F
at the bottom x-axis or °C at the top) and intersect the pressure and
salinity in the chart. From that point read the density on the y-axis.
Example: Density of Water
Given: Temperature = 200°F [93°C], pressure = 7,000 psi, and
salinity = 250,000 ppm.
Answer: Density of water = 1.15 g/cm 3 .
Example: Hydrogen Index of Salt Water
Given: Salinity of saltwater = 125,000 ppm.
Answer: Hydrogen index = 0.95.
Example: Hydrogen Index of Hydrocarbons
Given: Oil density = 0.60 g/cm 3 .
Answer: Hydrocarbon index = approximately 0.91.
Back to Contents
General
Density and Hydrogen Index of Natural Gas
Schlumberger
Gen -8
Gas
density
(g/cm 3 )
03
Gas gravity = 0.6
(Air = 1.0)
100^
/^ \W ^^^
^ inn . "
n?
0^.250^-^
^VSsoo^^
/^.350
' Gas
temperature
(°R
0.1
n
u
n gas
0.7
_: 0.6
_: 0.5
_: 0.4
_: 0.3
_: 0.2
_: o.i
3 o
2 4 6
Gas pressure x 1,000 (psia)
10
Gas
density
(g/cm 3 )
Pressure
17,500
15,000
12,500
10,000
7,500
5,000
2,500
14.7
© Schlumberger
100 200 300 400
Temperature (°F)
Purpose
This chart can be used to determine more than one characteristic
of natural gas under different conditions. The characteristics are
gas density (p g ), gas pressure, and hydrogen index (H gas ).
Description
For known values of gas density, pressure, and temperature, the value
of Hgas can be determined. If only the gas pressure and temperature
are known, then the gas density and Hgas can be determined. If the
gas density and temperature are known, then the gas pressure and
Hgas can be determined.
10
Example
Given: Gas density = 0.2 g/cm 3 and temperature = 200°F.
Find: Gas pressure and hydrogen index.
Answer: Gas pressure = approximately 5,200 psi and Hg as = 0.44.
Back to Contents
General
Sound Velocity of Hydrocarbons
Schlumberger
Gen -9
5,000
4,000
Sound 3 000
velocity
(ft/s)
2,000
1,000
Natural Gas
Temperature (°C)
100 150
Sound
slowness
(Us/ft)
50 100 150 200 250 300
Temperature (°F)
350
© Schlumberger
Purpose
This chart is used to determine the sound velocity (ft/s) and sound
slowness (jas/ft) of gas in the formation. These values are helpful in
sonic and seismic interpretations.
Description
Enter the chart with the temperature (Celsius along the top x-axis
and Fahrenheit along the bottom) to intersect the formation
pore pressure.
Back to Contents
General
Gas Effect on Compressional Slowness
Schlumberger
Gen-9a
200
Sandstorm
At c
(US/ft)
100
50
. 110|is/ft
. 90u.s/ft
i 70 us/ft
""-"N
\
xl
— -v^
C
© Schlumberger
20 40 60 80 100
Liquid saturation (%)
Wnnri's law (h = 5) Pnwnr law (f> = 3)
Purpose
This chart illustrates the effect that gas in the formation has on the
slowness time of sound from the sonic tool to anticipate the slowness
of a formation that contains gas and liquid.
Description
Enter the chart with the compressional slowness time (At c ) from the
sonic log on the y-axis and the liquid saturation of the formation on
the x-axis. The curves are used to determine the gas effect on the
basis of which correlation (Wood's law or Power law) is applied. The
slowing effect begins sooner for the Power law correlation. The
Wood's law correlation slightly increases At c values as the formation
liquid saturation increases whereas the Power law correlation
decreases At c values from about 20% liquid saturation.
12
Back to Contents
General
Gas Effect on Acoustic Velocity
Sandstone and Limestone
Schlumberger
Gen-9b
Sandstone
25
20
Velocity '^
(1,000 xft/s)
10
No gas
Gas bearing
^*"* > »^^
^
\^
^*^^
^
10 20 30
Porosity (p. u.)
40
Limestone
© Schlumberger
25
Velocity
(1,000 xft/s)
Mo gas
■0*v li ^
Gas bearing
20
15
\A
in
**■**&
V?*
5
""^fl^-
^
n
10 20 30
Porosity (p. u.)
40
Purpose
This chart is used to determine porosity from the compressional
wave or shear wave velocity (V p and V s , respectively).
Description
Enter V p or V s on the y-axis to intersect the appropriate curve. Read
the porosity for the sandstone or limestone formation on the x-axis.
< ►
Back to Contents
13
General
Schlumberger
Nuclear Magnetic Resonance Relaxation Times of Water
Gen-10
Longitudinal (Bulk) Relaxation
Time of Water
Relaxation
time (s)
100
10
1.0
0.1
0.01
ll-
20 60 100 140
Temperature (°C)
180
Transverse (Bulk and Diffusion)
Relaxation Time of Water
100
Relaxation
time (s)
10
T 2 (TE
= 0.2ms) =
1.0
-■-..
T 2 (TE =
0.32 ms)
•» -. w
""* •■.
" — —
"— -»
^ w
~
- - -
^
m
--...
T 2 (TE
= 1 ms
)
— ^~-
■ ^ _ —
""* ■■ .
■> \
n.oi
20 60 100 140 180
Temperature (°C)
D Schlumberger
Purpose
Longitudinal (Bulk) Relaxation Time of Pure Water
This chart provides an approximation of the bulk relaxation time
(Ti) of pure water depending on the temperature of the water.
Transverse (Bulk and Diffusion) Relaxation Time of Water
in the Formation
Determining the bulk and diffusion relaxation time (T2) from this
chart requires knowledge of both the formation temperature and
the echo spacing (TE) used to acquire the data. These data are pre-
sented graphically on the log and are the basis of the water or
hydrocarbon interpretation of the zone of interest.
Description
Longitudinal Relaxation Time
The chart relation is for pure water — the additives in drilling fluids
reduce the relaxation time (Ti) of water in the invaded zone. The
two major contributors to the reduction are surfactants added to the
drilling fluid and the molecular interactions of the mud filtrate con-
tained in the pore spaces and matrix minerals of the formation.
Transverse Relaxation Time
The relaxation time (T2) determination is based on the formation
temperature and echo spacing used to acquire the measurement.
The TE value is listed in the parameter section of the log. Using
the T2 measurement from a known water sand or based on local
experience further aids in determining whether a zone of
interest contains hydrocarbons, water, or both.
14
Back to Contents
General
Schlumberger
Nuclear Magnetic Resonance Relaxation Times of Hydrocarbons
Gen-11a
T,(s)
10
0.1
Longitudinal (Bulk) Relaxation
Time of Crude Oil
Light oil: 45°-60° APIff
Rd D7i;n/rm
3
1
M
edium ni
0.1
L|Q7R-nRRn/nm3-l
-T,
0.01
av
0.001
He
/oil: 10°-20° AP
p0.85-0.95 a
cm
ttttttl —
ttttttl —
0.0001
10 100 1,000 10,000 100,000
Viscosity (cp)
T,(s)
Transverse (Bulk and Diffusion) Relaxation
Time of Crude Oil
10
0.1
0.01
0.001
0.0001
0.1
TE - 2 ms
TE- 0.32 ms
TE - 1 ms
_ TE = 2 ms
10 100 1,000 10,000 100,000
Viscosity (cp)
Diffusion
(cm 2 /s)
Hyd
ocarbon Diffusion Coefficient
111- 3
m- 4
3il(9°at20°C
)
10- 5
— -""''--"
^
' x
— •
/ C
)il (40° at 20°
:)
10- 6
/
IfF
© Schlumberger
50 100 150
Temperature (°C)
200
Diffusion
(10- 5 cm 2 /s)
?n
Water Diffusion Coefficient
is
in
R
n
50 100 150
Temperature (°C)
200
Purpose
Longitudinal (Bulk) Relaxation Time of Crude Oil
This chart is used to predict the Ti of crude oils with various viscosi-
ties and densities or specific gravities to assist in interpretation of
the fluid content of the formation of interest.
Transverse (Bulk and Diffusion) Relaxation Time
Known values of T2 and TE can be used to approximate the viscosity
by using this chart.
Diffusion Coefficients for Hydrocarbon and Water
These charts are used to predict the diffusion coefficient of hydro-
carbon as a function of formation temperature and viscosity and
of water as a function of formation temperature.
Description
Longitudinal (Bulk) Relaxation Time
This chart is divided into three distinct sections based on the compo-
sition of the oil measured. The type of oil contained in the formation
can be determined from the measured Ti and viscosity determined
from the transverse relaxation time chart.
Transverse (Bulk and Diffusion) Relaxation Time
The viscosity can be determined with values of the measured T2 and
TE for input to the longitudinal relaxation time chart to identify the
type of oil in the formation.
Back to Contents
15
General
Schlumberger
Nuclear Magnetic Resonance Relaxation Times of Hydrocarbons
Gen-11b
35
30
25
20
15
10
5
Methane Diffusion Coefficient
^1,600 psi
3,000^
Diffusion
(1(Hcm 2 /s)
^S 3^oo__
^
'***■
^-^>-"
--"""''
0,JUU „
.-. — -'15,500 _
== = = =
-------
22,800
T,(s)
100
10
50 100 150
Temperature (°C)
Transverse (Bulk and Diffusion)
Relaxation Time of Methane
0.1
0.01
0.001
200
TE = 0.
2 ms
0.32 ms
lt =
^—
"^ j
E - ' m
-^
^
s
■^
-i — ^-** —
T-
= 2 ms
-^T
^
■"-«
io-*
10- 3
Diffusion (cm 2 /s)
10-
T,(s)
10
Longitudinal (Bulk) Relaxation
Time of Methane
■>
5 :: C
5C
>5°(
75°
7
8
1
1
R
^
-"*'
.,-•'"
s
y
**
y
„.--
-
4
y
^
*■
^
.....
'"
***'"
/ x
*
....
..-•
*
?
.-**
,»**
n
3,000 6,000 9,000 12,000
Pressure (psi)
1.2
1.0
08
Hydrogen Index of Live Hydroca
rbons and Gas
Hydrogen
index 0-6
04
02
0.2 0.4 0.6 0.8 1.0 1.2
Hydrocarbon density (g/cm 3 )
© Schlumberger
Purpose
Methane Diffusion Coefficient
This chart is used to determine the diffusion coefficient of methane
at a known formation temperature and pressure.
Longitudinal and Transverse Relaxation Times of Methane
These charts are used to determine the longitudinal relaxation time
(Ti) of methane by using the formation temperature and pressure
(see Reference 48) and the transverse relaxation time (T2) of
methane by using the diffusion and echo spacing (TE), respectively.
Hydrogen Index of Live Hydrocarbons and Gas
This chart is used to determine the hydrogen index from the hydro-
carbon density.
16
< ►
Back to Contents
General
Capture Cross Section of NaCI Water Solutions
Schlumberger
Purpose
The sigma value (E w ) of a saltwater solution can be determined from
this chart. The sigma water value is used to calculate the water satu-
ration of a formation.
Description
Charts Gen-12 and Gen-13 define sigma water for pressure condi-
tions of ambient through 20,000 psi [138 MPa] and temperatures
from 68° to 500°F [20° to 260°C]. Enter the appropriate chart for
the pressure value with the known water salinity on the y-axis and
move horizontally to intersect the formation temperature. The sigma
of the formation water for the intersection point is on the x-axis.
Example
Given: Water salinity = 125,000 ppm, temperature = 68°F at
ambient pressure, and formation temperature = 190°F
at 5,000 psi.
Find: E w at ambient conditions and E w of the formation.
Answer: E w = 69 c.u. and E w of the formation = 67 c.u.
If the sigma water apparent (£ W a) is known from a clean water
sand, then the salinity of the formation can be determined by enter-
ing the chart from the sigma water value on the x-axis to intersect
the pressure and temperature values.
< ►
Back to Contents
continued on next page
17
General
Capture Cross Section of NaCI Water Solutions
Schlumberger
Gen-12
(former Tcor-2a)
© Schlumberger
Equivalent water salinity
(1,000 xppm NaCI)
300
300
275
250
225
200
175
150
125
100
75
50
25
275
250
225
200
/4
<*
*/.
^//
300
275
250
225
200
;/r
4l
§
„<?/
<$?
-175 j
/ ZMZ,
V
Aso
150j
300
275
250
225
200
175
150
125
100
75
50
25
^125
100
75
50
25
n>
4
§y
«#
//
100
75
50
25
] 10 20 30 40 50 60 70 80 90 100 110 120 130 V
S w (c.u.)
10
Back to Contents
General
Capture Cross Section of NaCI Water Solutions
Schlumberger
Gen-13
(former Tcor-2b)
© Schlumberger
Equivalent water salinity
(1,000 xppm NaCI)
300
300
275
250
225
200
175
150
125
100
75
50
25
i
Jh -
275
250
225
200
«
J>//,
J? /A
300
275
250
225
200
4%
.«
&S
v&
<?
300
275
250
225
200
175
150
125
100
75
50
25
^125
^150
150 y
125/
<,
100
75
50
25
y "$£
2*
Vs
^
7/
J
•v
100
75
50
25
] 10 20 30 40 50 60 70 80 90 100 110 120 130 1
EJc.u.)
to
Purpose
Chart Gen-13 continues Chart Gen-12 at higher pressure values for
the determination of E w of a saltwater solution.
Back to Contents
19
General
Capture Cross Section of Hydrocarbons
Schlumberger
Purpose
Sigma hydrocarbon (Eh) for gas or oil can be determined by using
this chart. Sigma hydrocarbon is used to calculate the water satura-
tion of a formation.
Description
One set of charts is for measurement in metric units and the other
is for measurements in "customary" oilfield units.
For gas, enter the background chart of a chart set with the reser-
voir pressure and temperature. At that intersection point move left
to the y-axis and read the sigma of methane gas.
For oil, use the foreground chart and enter the solution gas/oil
ratio (GOR) of the oil on the x-axis. Move upward to intersect the
appropriate API gravity curve for the oil. From this intersection
point, move horizontally left and read the sigma of the oil on
the y-axis.
Example
Given:
Find:
Answer:
Reservoir pressure = 8,000 psi, reservoir temperature
300°F, gravity of reservoir oil = 30°API, and solution
GOR = 200.
Sigma gas and sigma oil.
Sigma gas = 10 c.u. and sigma oil = 21.6 c.u.
20
Back to Contents
General
Capture Cross Section of Hydrocarbons
Schlumberger
Gen-14
(former Tcor-1)
20.0'
17.5
15.0
12.5
10.0
7.5
5.0
2.5
4,000
Reservoir pressure (psia)
8,000 12,000
16,000 20,000
Me
thane
. 200
300
^
Customary
400
'. 500
Temperati
I
ire(°F)
Liquid hydrocarbons
:22
I ill
,30°, 40°, and 50° API
;t^
.20
18
(c.u
)
20° a
nd 60° API
/
\
%
%
16
s
S, (
10
100 1,000
Solution G0R (ft 3 /bbl)
10,000
I h (c.u.]
20.0
17.5
15.0
12.5
10.0
7.5
5.0
2.5
Reservoir pressure (mPa)
14 28 41 55 69 83 97 110 124 138
Me
ithane
^52-
,aso-
Metric
. 205-
. 260'
Terr
peratur
e(°C)
. IT
Liquid hydrocarbons
0.78 to 0.88 mg/m 3
.20
c.u
)
0J
4c
rO
9'
In
ig/
Tl 3 /
^
5s
.18
s
*
*
.<
\
1°
_16
.
© Schlumberger
10 100
Solution G0R(m 3 /m 3 )
1,000 2,000
< ►
Back to Contents
General
EPT* Propagation Time of NaCI Water Solutions
Schlumberger
Gen-15
(former EPTcor-1)
qn
20° C
< vr
**? -250°F
80
'*' III
/ ,* ,.- 2UU h
+ * <»' <•
i ' * III
S' ' -*'*~ ~ 80°C
70
/? , '*-* '* -175°F
/ ' '* mi ii
4*
u-
f
.y e*" _, 150°F
}•
y •' .' .^ ' _ — o
s * y
J S '
' ■ ■'Mill
Jt +Z'
en £ /*
.?* S -" ,^125°F
60 / r t' *■
■* .^
<L S* '
' x'
J V /-
rf' X' »■
Jf /? 7
' •' ' _ .»r< _
, . , i 7 ^ „^ ^ -
t ns/m jf tl 7 +
^ . "•_. -""" I UU r
' ----2-^
jt 1 ^t- /. ' «,
.. £-
en t & t ^< r
=.^
50 iWy 1 - - 7 A
'?■
xf 75°F
Jttf/j ■' •* ^
iLt-f^ji ^ i£
-- — 20°C
>m ty ' ' ^
* *"* ..— •"
II\f\ i ' ' j ' * *<£
-^ -^ '""
II if W /' f / **
*■ „. '"^
il\f\m ' i 4* ^
^ *"*
ft 1 fft r f '' . " • *"
40 'f/wW/ S ■' '"
N i ff // / S ft"* '^
Ilta/jf/ J r* j*^
III ff/// J y
/ iff/// / jf *r
ffflMut/ / f.S S^
m&V A xi*^
mar^^y^^ 1 ^
M/F^y^^^
immt ^^
30 ~"9
~*m
*M
n
6-
r
20 _
50 100
Equivalent water salinity
*Markof Schlumberger
© Schlumberger
150 200 250
1,000 xppm or g/kg NaCI)
Purpose
This chart is designed to determine the propagation time (t pw ) of
saltwater solutions. The value of t pw of a water zone is used to deter-
mine the temperature variation of the salinity of the formation water.
Description
Enter the chart with the known salinity of the zone of interest and
move upward to the formation temperature curve. From that inter-
section point move horizontally left and read the propagation time
of the water in the formation on the y-axis. Conversely, enter the
chart with a known value of t pw from the EPT Electromagnetic
Propagation Tool log to intersect the formation temperature curve
and read the water salinity at the bottom of the chart.
22
Back to Contents
General
EPT* Attenuation of NaCI Water Solutions
Schlumberger
Gen-16
(former EPTcor-2)
5,000
4,000
Attenuation, 3 - 000
A
(dB/m)
2,000
1,000
i9n°r
,» '*"250°F
" '** " 100°C
+*."* ,* -^^.^ 200°F
^*~* -.** .- '* - ( -* , "!l7R F-
^ *'-' -**^ 150°F
/' r * + w •'' ~~ 60°C
^€ * * ^*' ^* *• '- ^^m25°F"
_/ *t£^++* .^-^^-^ _; 4U u
- *^ ■* •*"**' «-■* -■=• z-s:inn°F-
y , , S -* ' -^ -t ■- i I I I I
-X ZZ £ >^' ^£* ***" -*"" Tr-or
^ *z? K ^ *"* —- 75°F
2_j5 ' z z '2*~ *• "* -***
a' // / s/ ^ >£ J —** ■■"*"
ZZZZ Z _j' j_.^ ** «•■*"
frfr t> *■ $* - ''*
/ ft A/ / j j, •/ **•**'
i fix// J / ^ "^ ^
1 ffs\ff, / /f *'■*'
ilfflAf * /' y? 1
limfff/ J? / ^
IlKrW /^"
1mm/ f /*
Imi/fJp
ml// aV
Wm/m
mm
w\
50 100 150 200
Equivalent water salinity (kppm or g/kg NaCI)
250
EPT-D Spreading Loss
"N-
s,
*^
'v
'.
>.
>
\
^
"^k
\
\
k
>
^
.
\
k
^
^
1
c
1
C
>
s.
3
L
3
A
\
V
t
3
L
\
^
r
_l
-40
-60
-80
-100
Correction
" 12 ° toEATT
(dB/m)
-140
-160
-180
-200
*Markof Schlumberger
© Schlumberger
5 10 15 20 25 30
Uncorrected t p i (ns/m)
Purpose
This chart is designed to estimate the attenuation of saltwater solu-
tions. The attenuation (A w ) value of a water zone is used in conjunc
tion with the spreading loss determined from the EPT propagation
time measurement (t p i) to determine the saturation of the flushed
zone by using Chart SatOH-8.
Description
Enter the chart with the known salinity of the zone of interest and
move upward to the formation temperature curve. From that intersec-
tion point move horizontally left and read the attenuation of the water
in the formation on the y-axis. Conversely, enter the chart with a known
EATT attenuation value of A w from the EPT Electromagnetic
Propagation Tool log to intersect the formation temperature curve
and read the water salinity at the bottom of the chart.
23
Back to Contents
General
EPT* Propagation Time-Attenuation Crossplot
Sandstone Formation at 150°F [60°C]
Schlumberger
Gen-16a
1,000
900
800
700
600
Attenuation
(dB/m) 500
400
300
200
100
L
Sandstor
1 1 1 1 \/,'Y.s/s
R mfa from EPT log
ohm-m) 0.02 'V 0.05' ,
9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25
t p i (ns/m)
*Markof Schlumberger
© Schlumberger
Purpose
This chart is used to determine the apparent resistivity of the mud
filtrate (Rmfa) from measurements from the EPT Electromagnetic
Propagation Tool. The porosity of the formation (<|)ept) can also be
estimated. Porosity and mud filtrate resistivity values are used in
determining the water saturation.
Description
Enter the chart with the known attenuation and propagation time
(t p i). The intersection of those values identifies Rmfa and (|)ept from
the two sets of curves. This chart is characterized for a sandstone
formation at a temperature of 150°F [60°C].
Example
Given: Attenuation = 300 dB/m and t p i = 13 ns/m.
Find: Apparent resistivity of the mud filtrate and EPT porosity.
Answer: Rmf a = 0.1 ohm-m and (|>ept = 20 p.u.
24
< ►
Back to Contents
Gamma Ray — Wireline
Scintillation Gamma Ray — 3%- and 1%-in. Tools
Gamma Ray Correction for Hole Size and Barite Mud Weight
Schlumberger
GR-1
(former GR-1)
Scintillation Gamma Ray
Correction
factor
10.0
7.0
5.0
3.0
2.0
1.0
0.7
0.5
0.3
•
*
***
3%-
in. tool, centered ,.*"
„-••'
1 n /i6-in. tool.
centered
3 3 /8-in. tool.
sccentered
l 1 Vie-in. toe
1, eccentered
■*»2^
'€£Z- — """"
-■-J^**^
'■^
10
15
20
t(g/cm 2 )
25
30
35
40
© Schlumberger
Purpose
This chart provides a correction factor for measured values of forma-
tion gamma ray (GR) in gAPI units. The corrected GR values can be
used to determine shale volume corrections for calculating water
saturation in shaly sands.
Description
The semilog chart has the t factor on the x-axis and the correction
factor on the y-axis.
The input parameter, t, in g/cm 2 , is calculated as follows:
W,
mud
8.345
2.54(d h ) 2.54( dsonde )
where
W m ud = mud weight (lbm/gal)
dj, = diameter of wellbore (in.)
dsonde = outside diameter (OD) of tool (in.).
Example
Given: GR = 36 API units (gAPI), d h = 12 in, mud weight =
12 lbm/gal, tool OD = 3% in., and the tool is centered.
Find: Corrected GR value.
Answer:
12
8.345
2.54(12) 2.54(3.375)
: 15.8 g/cm .
Enter the chart at 15.8 on the x-axis and move upward to
intersect the 3 3 /s-in. centered curve. The corresponding
correction factor is 1.6.
1.6 x 36 gAPI = 58 gAPI.
< ►
Back to Contents
25
Gamma Ray — Wireline
Scintillation Gamma Ray — 3%- and 1%-in. Tools
Gamma Ray Correction for Barite Mud in Various-Size Boreholes
Schlumberger
GR-2
(former GR-2)
1.2
1.0
0.8
0.6
0.4
0.2
1%-in.
tool, conterod „
--''
,.■*"
""
^ «*»
.•,-*• ""'
vv
G-in. tool
ecconterod
»» — "**
_ -* *""
-"""
___--
-^s^z
-~^J1_
3%7n. too
, centored
^, ■?_
^ ^ -*
^i^
_ J
3 3 /s-in.
tool, eccentered
1
10 11 12 13 14 15
Mud weight (Ibm/gal)
16
17
19
20
1.2
1.0
0.8
F bh 0.6
0.4
0.2
" "^ ^
„ - -
3 /8-in. tool y
m*
/ 4*-
"'l"/i6-in.1
ool
' S
A
S
/s
4 5 6
dh-d sond0 (in.)
10
© Schlumberger
Purpose
These charts are used to further correct the GR reading for various
borehole sizes.
Description
Two components needed to complete correction of the GR reading
are determined with these charts: barite mud factor (B mu d) and
borehole function factor (Fbh)-
Example
Given: Borehole diameter = 6.0 in., tool OD = 3% in., the tool
is centered, mud weight = 12 lbm/gal, measured
GR = 36 gAPI.
Find: Corrected GR value.
Answer:
Enter the upper chart for B mu d versus mud weight at
12 lbm/gal on the x-axis. The intersection point with the
3 3 /8-in. centered curve is B muc i < 0.15 on the y-axis.
Determine (dh - d son de) as 6 - 3.375 = 2.625 in. and enter
26
that value on the lower chart for Fbh versus
(dh - dsonde) on the x-axis. Move upward to intersect
the 3%-in. curve, at which Fbh = 0.81.
Determine the new value of t using the equation from
Chart GR-1:
W,
mud
8.345
12
1.345
2.54(d h ) 2.54( dsonde )
2 2
2.54(6) 2.54(3.375)
: 4.8 g/cm .
The correction factor determined from Chart GR-1 is 0.9£
The complete correction factor is
(Chart GR-1 correction factor) x [1 + (B mu d x Fbh)]
= 1.12 x[l + (0.15x0.81)] =1.26.
Corrected GR = 36 x 1.26 = 45.4 gAPI.
Back to Contents
Gamma Ray — Wireline
Scintillation Gamma Ray — 3%- and 1%-in. Tools
Borehole Correction for Cased Hole
Schlumberger
GR-3
(former GR-3)
10.0
Scintillation Gamma Ray
7.0
5.0
3.0
2.0
Correction
factor
1.0
0.7
0.5
0.3
3%-in. tool
1 n /iG-in. tool
^, — '^>-"'
C
© Schlumberger
5 10 15 20 25 30 35 40
t(g/cm 2 )
Purpose
This chart is used to compensate for the effects of the casing,
cement sheath, and borehole fluid on the GR count rate in cased
holes for conditions of an eccentered 3 3 /s-in. tool in an 8-in. borehole
with 10-lbm/gal mud.
Description
In small boreholes the count rate can be too large, and in larger
boreholes the count rate can be too small. The chart is based on
openhole Chart GR-1, modified by laboratory and Monte Carlo
calculations to provide a correction factor for application to
the measured GR count rate in cased hole environments:
Example
Given:
2.54
2
W,
8M5 ( d IDcsg-
sonde
'cs g (d
ODcsg "iDcsg
P cement \% d ODcsg
Find:
Answer:
GR = 19 gAPI, hole diameter (dh) = 12 in., casing OD
(doDcsg) = 9 5 /s in. and 43.5 lbm/ft, casing ID (dmcsg) =
8.755 in., casing density (p cs g) = 7.96 g/cm 3 , tool OD
(dsonde) = 3% in., cement density (pcement) = 2.0 g/cm 3 ,
and mud weight (W m ) = 8.345 lbm/gal.
Corrected cased hole GR value.
The chart input factor calculated with the equation is
t = 21.7 g/cm 2 . Enter the chart at 21.7 on the x-axis. At
the intersection point with the 3%-in. curve, the value of
the correction factor on the y-axis is 2.0. The GR value is
corrected by multiplying by the correction factor:
19 gAPI x 2.0 = 38 gAPI.
Back to Contents
27
Gamma Ray— LWD
SlimPulse* and E-Pulse* Gamma Ray Tools
Borehole Correction for Open Hole
Schlumberger
GR-6
Correction
factor
*Markof Schlumberger
© Schlumberger
11
10
9
8
7
6
5
4
3
2
1
17.5-
n. bit"
13.5-
n. bit
12.25-
in. bit
9.875
8.5-
-in. bi
n. bit
t
,7-in
. bit "
i
9 10
11 12 13 14
Mud weight (Ibm/gal)
15
16
17
18
19
Purpose
This chart is used to provide a correction factor for gamma ray
values measured with the SlimPulse third-generation slim measure-
ments-while-drilling (MWD) tool or the E-Pulse electromagnetic
telemetry tool. These environmental corrections for mud weight
and bit size are already applied to the gamma ray presented on
the logs.
Description
Enter the chart with the mud weight on the x-axis and move
upward to intersect the appropriate openhole size. Interpolate
between lines as necessary. At the intersection point, move
horizontally left to the y-axis to read the correction factor that
the SlimPulse or E-Pulse gamma ray value was multiplied by to
obtain the corrected gamma ray value in gAPI units.
28
Back to Contents
Gamma Ray— LWD
ImPulse* Gamma Ray — 4.75-in. Tool
Borehole Correction for Open Hole
Schlumberger
GR-7
1.75
1.50
Correction , nc
factor
1.00
0.75
8.5-in. bit
__7-ir
_ 6-ir
. bit'
. bit -
*Markof Schlumberger
© Schlumberger
9 10 11 12 13 14 15 16 17 18 19
Mud weight (Ibm/gal)
Purpose
This chart is used to provide a correction factor for gamma ray
values measured with the ImPulse integrated MWD platform. These
environmental corrections for mud weight and bit size are already
applied to the gamma ray presented on the logs.
Description
Enter the chart with the mud weight on the x-axis and move
upward to intersect the appropriate bit size. Interpolate between
lines as necessary. At the intersection point, move horizontally left
to the y-axis to read the correction factor that the ImPulse gamma
ray value was multiplied by to obtain the corrected gamma ray
value in gAPI units.
Back to Contents
29
Gamma Ray— LWD
PowerPulse* and TeleScope* Gamma Ray — 6.75-in. Tools
Borehole Correction for Open Hole
Schlumberger
GR-9
PowerPulse and TeleScope Gamma Ray
ann
2.75
2.50
2.25
12.25
in. bil
Correction
factor
2.00
10.625-in. bit
—--T 1 1
1.75
l___—
9.875-in. bit
8.75-in. bit —
m „
_ —
---
- — """
1.50
- rr t
.
rtrr
-8.5-in. bit"
r^=
- = ^ :
~^ r=z
- — *"
1.25
1.00
E
9 10
11 12 13 14 15
16
17
18
19
Mud weight (Ibm/gal)
*Markof Schlumberger
© Schlumberger
Purpose
This chart is used to provide a correction factor for gamma ray values
measured with the PowerPulse 6.75-in. MWD telemetry system and
TeleScope 6.75-in. high-speed telemetry-while-drilling service.
These environmental corrections for mud weight and bit size are
already applied to the gamma ray presented on the logs.
Description
Enter the chart with the mud weight on the x-axis and move upward
to intersect the appropriate bit size. Interpolate between lines as
necessary. At the intersection point, move horizontally left to the
y-axis to read the correction factor that the PowerPulse or
TeleScope gamma ray value was multiplied by to obtain the cor-
rected gamma ray value in gAPI units.
30
Back to Contents
Gamma Ray— LWD
Schlumberger
PowerPulse* Gamma Ray — 8.25-in. Normal-Flow Tool
Borehole Correction for Open Hole
GR-10
5.00
4.75
4.50
4.25
4.00
Correction qyc
factor
3.50
3.25
3.00
2.75
2.50
17.5-
n. bit
14.75-
in. bi
13.5-
n. bit
12.25-
in. bit
^ —
-"-"
--"
.-'■
0.625
-in. b
t"
.--
m , —
---
_--
--"
--"
_
_--
--"
■ --'
--"
_
_ - -
--"
9.875
in. bil
"*
.--
-~~
i
*Markof Schlumberger
© Schlumberger
9 10 11 12 13 14 15
Mud weight (Ibm/gal)
16 17 18 19
Purpose
This chart is used to provide a correction factor for gamma ray values
measured with the PowerPulse 8.25-in. normal-flow MWD telemetry
system. These environmental corrections for mud weight and bit
size are already applied to the gamma ray presented on the logs.
Description
Enter the chart with the mud weight on the x-axis and move upward
to intersect the appropriate bit size. Interpolate between lines as
necessaiy. At the intersection point, move horizontally left to the y-axis
to read the appropriate correction factor that the PowerPulse gamma
ray value was multiplied by to obtain the corrected GR value in gAPI
units.
Back to Contents
Gamma Ray— LWD
Schlumberger
PowerPulse* Gamma Ray — 8.25-in. High-Flow Tool
Borehole Correction for Open Hole
GR-11
4.25
4.00
3.75
3.50
3.25
Correction 3 qq
factor
2.75
2.50
2.25
2.00
1.75
17.5-
n. bit
14.7
5-in. bit
13.5-ii
1. bit
1
2.25-ir
i. bit
10.6
25-in.
bit
. 9.8
_--
.--
- "* *"
_ ^ -
--"
--■
.--
— ■"*
_ _ -
---
75-in.
bit
.--
--"
--*
--■
- — ""
_--
---
---
— ■*
i
*Markof Schlumberger
© Schlumberger
9
10
11 12 13 14 15 16 17 18
Mud weight (Ibm/gal)
19
Purpose
This chart is used to provide a correction factor for gamma ray values
measured with the PowerPulse 8.25-in. high-flow MWD telemetry
system. These environmental corrections for mud weight and bit
size are already applied to the gamma ray presented on the logs.
Description
Enter the chart with the mud weight on the x-axis and move upward
to intersect the appropriate bit size. Interpolate between lines as
necessary. At the intersection point, move horizontally left to the
y-axis to read the correction factor that the PowerPulse gamma ray
value was multiplied by to obtain the corrected gamma ray value in
gAPI units.
32
Back to Contents
Gamma Ray— LWD
Schlumberger
PowerPulse* Gamma Ray — 9-in. Tool
Borehole Correction for Open Hole
GR-12
7.50
7.00
6.50
6.00
5.50
Correction gnn
factor
4.50
4.00
3.50
3.00
2.50
22-in.
bit
1
7.5-in
bit
14.75
-in. b
t
: 13.5
-in. bi
_ J
--"
2.25-
n. bit
--"
.--'
_--
---
— ""*
.10
625-i
l. bit
—
—
*Markof Schlumberger
© Schlumberger
9 10 11 12 13 14 15 16 17
Mud weight (Ibm/gal)
18
19
Purpose
This chart is used to provide a correction factor for gamma ray values
measured with the PowerPulse 9-in. MWD telemetry system. These
environmental corrections for mud weight and bit size are already
applied to the gamma ray presented on the logs.
Description
Enter the chart with the mud weight on the x-axis and move upward
to intersect the appropriate bit size. Interpolate between lines as
necessary. At the intersection point, move horizontally left to the
y-axis to read the correction factor that the PowerPulse gamma ray
value was multiplied by to obtain the corrected gamma ray value in
gAPI units.
Back to Contents
33
Gamma Ray— LWD
PowerPulse* Gamma Ray — 9.5-in. Normal-Flow Tool
Borehole Correction for Open Hole
Schlumberger
GR-13
8.00
7.50
7.00
6.50
6.00
Correction gen
factor
5.00
4.50
4.00
3.50
3.00
in. bi
LL
t
1;
.5-inT
bit
147
5-in.
lit
3.5-i
l. bit
.--
---
--""
— """
. - - •
.--
---
.12.2
5-in. t
it
---
" '
25-in.
bit
—
" — "~
*Markof Schlumberger
© Schlumberger
9 10 11 12 13 14 15 16 17 18 19
Mud weight (Ibm/gal)
Purpose
This chart is used to provide a correction factor for gamma ray values
measured with the PowerPulse 9.5-in. normal-flow MWD telemetry
system. These environmental corrections for mud weight and bit
size are already applied to the gamma ray presented on the logs.
Description
Enter the chart with the mud weight on the x-axis and move upward
to intersect the appropriate bit size. Interpolate between lines as
necessary. At the intersection point, move horizontally left to the
y-axis to read the correction factor that the PowerPulse gammma ray
value was multiplied by to obtain the corrected gamma ray value in
gAPI units.
34
Back to Contents
Gamma Ray— LWD
Schlumberger
PowerPulse* Gamma Ray — 9.5-in. High-Flow Tool
Borehole Correction for Open Hole
GR-14
Correction
factor
*Markof Schlumberger
© Schlumberger
8 0(1
7.50
7.00
6.50
6.00
5.50
5.00
4.50
4.00
3.50
3.00
2.50
?no
2;
!-in. bit
17.5-
n. bit
14.75
-in. bi
t
.13.5
-in. bi
t
_
_--
--"
--"
• --"
15
.25-ir
. bit"
— " "
---
--10.I
525-in
bit
{
9 10
11 12 13 14 15
Mud weight (Ibm/gal)
16 17 18 19
Purpose
This chart is used to provide a correction factor for gamma ray values
measured by the PowerPulse 9.5-in. high-flow MWD telemetry sys-
tem. These environmental corrections for mud weight and bit size
are already applied to the gamma ray presented on the logs.
Description
Enter the chart with the mud weight on the x-axis and move upward
to intersect the appropriate bit size. Interpolate between lines as
necessary. At the intersection point, move horizontally left to the
y-axis to read the correction factor that the PowerPulse gamma ray
value was multiplied by to obtain the corrected gamma ray value in
gAPI units.
Back to Contents
35
Gamma Ray— LWD
Schlumberger
geoVISION675* GVR* Gamma Ray— 6.75-in. Tool
Borehole Correction for Open Hole
GR-15
Correction
factor
*Markof Schlumberger
© Schlumberger
?75
2.50
2.25
2.00
1.75
1.50
1.25
1.00
0.75
12.25-
in. bil
.10.625-in.
bit
9.
375-in
. bit"
3 7R-i
i hit
o.o-in
. Dlt ~
{
9 10
11 12 13 14 15
Mud weight (Ibm/gal)
16
17
18
19
Purpose
This chart is used to provide a correction factor for gamma ray
values measured with the GVR resistivity sub of the geoVISION 6 3 /4-in.
MWD/LWD imaging system. These environmental corrections for
mud weight and bit size are already applied to the gamma ray
presented on the logs.
Description
Enter the chart with the mud weight on the x-axis and move upward
to intersect the appropriate bit size. Interpolate between lines as
necessary. At the intersection point, move horizontally left to the
y-axis to read the correction factor that the GVR gamma ray value was
multiplied by to obtain the corrected gamma ray value in gAPI units.
36
Back to Contents
Gamma Ray— LWD
RAB* Gamma Ray — 8.25-in. Tool
Borehole Correction for Open Hole
Schlumberger
GR-16
Correction
factor
*Markof Schlumberger
© Schlumberger
3 no
2.75
2.50
2.25
2.00
1.75
1.50
1.25
1.00
0.75
50
17.5-in.
bit '
,14.75-in. bit
— 13.5-in. bit
1 2.25
-in. bi
t
625-i
n. bit
■ -9.8"
'5-in.
bit- -
- - 10
f
9
10
11
12 13 14 15 16
Mud weight (Ibm/gal)
17
18
19
Purpose
This chart is used to provide a correction factor for gamma ray values
measured with the RAB Resistivity-at-the-Bit 8.25-in. tool. These envi-
ronmental corrections for mud weight and bit size are already
applied to the gamma ray presented on the logs.
Description
Enter the chart with the mud weight on the x-axis and move upward
to intersect the appropriate bit size. Interpolate between lines as
necessary. At the intersection point, move horizontally left to the
y-axis to read the correction factor that the RAB gamma ray value
was multiplied by to obtain the corrected gamma ray value in gAPI
units.
Back to Contents
37
Gamma Ray— LWD
Schlumberger
arcVISI0N475* Gamma Ray — 4.75-in. Tool
Borehole Correction for Open Hole
GR-19
1.75
1.50
Correction -i 25
factor
1.00
0.75
8.5-in. bit
_7-in
_ 6-in
. bit"
. bit~
i
*Markof Schlumberger
© Schlumberger
9 10 11 12 13 14 15 16 17 18 19
Mud weight (Ibm/gal)
Purpose
This chart is used to provide a correction factor for gamma ray values
measured with the arcVISION475 4 3 /4-in. drill collar resistivity tool.
These environmental corrections for mud weight and bit size are
already applied to the gamma ray presented on the logs.
Description
Enter the chart with the mud weight on the x-axis and move upward
to intersect the appropriate bit size. Interpolate between lines as
necessary. At the intersection point, move horizontally left to the
y-axis to read the correction factor that the arcVISION475 gamma
ray value was multiplied by to obtain the corrected gamma ray value
in gAPI units.
38
Back to Contents
Gamma Ray— LWD
Schlumberger
arcVISION675* Gamma Ray — 6.75-in. Tool
Borehole Correction for Open Hole
GR-20
3.50
3.25
3.00
2.75
2.50
2.25
Correction 200
factor
1.75
1.50
1.25
1.00
0.75
0.50
12.25-
in. bil
10.625-
n hit
9 875-in bit"
i
*Markof Schlumberger
© Schlumberger
9 10 11 12 13 14 15 16 17 18 19
Mud weight (Ibm/gal)
Purpose
This chart is used to provide a correction factor for gamma ray values
measured with the arcVISION675 6 3 /4-in. drill collar resistivity tool.
These environmental corrections for mud weight and bit size are
already applied to the gamma ray presented on the logs.
Description
Enter the chart with the mud weight on the x-axis and move upward
to intersect the appropriate bit size. Interpolate between lines
as necessary. At the intersection point, move horizontally left to
the y-axis to read the appropriate correction factor that the
arcVISION675 gamma ray value was multiplied by to obtain
the corrected gamma ray value in gAPI units.
Back to Contents
39
Gamma Ray— LWD
Schlumberger
arcVISION825* Gamma Ray — 8.25-in. Tool
Borehole Correction for Open Hole
GR-21
Correction
factor
*Markof Schlumberger
© Schlumberger
son
2.75
2.50
2.25
2.00
1.75
1.50
1.25
1.00
0.75
50
17.5
-in. bit
14.7E
-in. bit
1
2.25-
3.5-in
bit
1
n. bit
: --
---
- —
:::
_- 9
875-i
i. bit
{
9 10 11 12 13 14 15
Mud weight (Ibm/gal)
16
17
18
19
Purpose
This chart is used to provide a correction factor for gamma ray values
measured with the arcVISION825 8!/4-in. drill collar resistivity tool.
These environmental corrections for mud weight and bit size are
already applied to the gamma ray presented on the logs.
Description
Enter the chart with the mud weight on the x-axis and move upward
to intersect the appropriate bit size. Interpolate between lines as
necessary. At the intersection point, move horizontally left to
the y-axis and read the appropriate correction factor that the
arcVISION825 gamma ray value was multiplied by to obtain
the corrected gamma ray value in gAPI units.
40
Back to Contents
Gamma Ray— LWD
Schlumberger
arcVISION900* Gamma Ray— 9-in. Tool
Borehole Correction for Open Hole
GR-22
5.5
5.0
4.5
4.0
3.5
Correction on
factor
2.5
2.0
1.5
1.0
0.5
»2-in.'
bit
7.5-i
t. bit
1
4.75-i
n. bit
— 13
n. bit
"■ ■"
I0.625in. b
i
*Markof Schlumberger
© Schlumberger
9 10 11 12 13 14 15 16 17 18 19
Mud weight (Ibm/gal)
Purpose
This chart is used to provide a correction factor for gamma ray values
measured with the arcVISION900 9-in. drill collar resistivity tool.
These environmental corrections for mud weight and bit size are
already applied to the gamma ray presented on the logs.
Description
Enter the chart with the mud weight on the x-axis and move upward
to intersect the appropriate bit size. Interpolate between lines as
necessaiy. At the intersection point, move horizontally left to
the y-axis and read the appropriate correction factor that the
arcVISION900 gamma ray value was multiplied by to obtain the
corrected gamma ray value in gAPI units.
Back to Contents
41
Gamma Ray— LWD
arcVISI0N475* Gamma Ray— 4.75-in. Tool
Potassium Correction for Open Hole
Schlumberger
GR-23
Correction
subtracted
for 5-wt%
potassium
(gAPI)
*Markof Schlumberger
© Schlumberger
inn
8
9n
8n
7n
6n
sn
4n
3n
2n
in
n
/"
20 ppg ^
^
^^O^J6 ppg ^^
^- — "^14 ppg __ J2 ppg"
-'' ^ JO ppg__'_
--"1.-^'£3ppc
?ppg.1-'
j«^]j«^\^^^''^ "*
-c-'~~~
<^' : '°-
(
i 8 10 12 14 16 1
Hole size (in.)
Purpose
This chart is used to provide a correction that is subtracted from
the borehole-corrected gamma ray from the arcVISION475 4 3 /4-in.
tool. Environmental corrections for mud weight and bit size are
already applied to the gamma ray presented on the logs.
Description
This chart is for illustrative purposes only. The indicated correction
is already applied to the gamma ray log.
To determine the correction that was applied to the log output,
enter the chart with the borehole size on the x-axis and move upward
to intersect the downhole mud weight. From the intersection point
move horizontally left to read the correction in gAPI units that was
subtracted from the borehole-corrected data.
Charts GR-24 through GR-26 are similar to Chart GR-23 for
different arcVISION tool sizes.
42
Back to Contents
Gamma Ray— LWD
arcVISION675* Gamma Ray— 6.75-in. Tool
Potassium Correction for Open Hole
Schlumberger
GR-24
50
Correction
subtracted
for 5-wt%
potassium
(gAPI)
_ 20ppg -
4F
-18ppg
4n
. 16 ppg-
35
. I4ppg
30
I2ppg"
?F
„,. «- ""
.,-'"'
._- ioppg
?n
IF
^-
'"""
.. — — **"
"iTfbppg
- 9 ppglll
— — — —
m
■»■*"" _ -
■*"* — — " ' ""
F
n
8.E
9.0
9.F
10.0
10.E 11.0
Hole size (in.)
11.5
12.0
12.5
13.0
*Markof Schlumberger
© Schlumberger
Purpose
This chart is used to provide a correction that is subtracted from
the borehole-corrected gamma ray from the arcVISION675 6 3 /4-in.
tool. Environmental corrections for mud weight and bit size are
already applied to the gamma ray presented on the logs.
Description
This chart is for illustrative purposes only. The indicated correction
is already applied on the gamma ray log.
To determine the correction that was applied to the log output,
enter the chart with the borehole size on the x-axis and move
upward to intersect the downhole mud weight. From the intersection
point move horizontally left to read the correction in gAPI units that
was subtracted from the borehole-corrected data.
Back to Contents
43
Gamma Ray— LWD
arcVISION825* Gamma Ray — 8.25-in. Tool
Potassium Correction for Open Hole
Schlumberger
GR-25
100
90
80
70
60
Correction
subtracted
for5-wt% 50
potassium
(OAPI)
40
30
20
10
20 ppg
1R nnn
""^^ ___
16 ppg
^ — ""*
----""
/ ^^ J 4 ppg
„ — *"
*""" ---■""""'
''''"'---"
12
ppg ,-'
. - - ** V- - *■ *■ "
"*
,«•"* 'U PP9
,'''9ppg,'-
8.3 ppg
10
12
14 IE
Hole size (in.)
20
22
*Markof Schlumberger
© Schlumberger
Purpose
This chart is used to provide a correction that is subtracted from
the borehole-corrected gamma ray from the arcVISION825 8Vi-in,
tool. Environmental corrections for mud weight and bit size are
already applied to the gamma ray presented on the logs.
Description
This chart is for illustrative purposes only. The indicated correction
is already applied on the gamma ray log.
To determine the correction that was applied to the log output,
enter the chart with the borehole size on the x-axis and move upward
to intersect the downhole mud weight. From the intersection point
move horizontally left to read the correction in gAPI units that was
subtracted from the borehole-corrected data.
44
Back to Contents
Gamma Ray— LWD
arcVISION900* Gamma Ray— 9-in. tool
Potassium Correction for Open Hole
Schlumberger
GR-26
120
Correction
subtracted
for 5-wt%
potassium
(gAPI)
inn
an
^^1
20 ppg'
8ppg^
„-•"''
fin
^16 p|
14ppg
'9
,-''''
-"'"
,-'''
_-.--
'-'''
4n
«•
f
JOppg
)2ppg'
„-''-
,-.-''
~ ~~~'
?n
'8.3 ppg
?ppg,-
n
10
11
12
13
14 15
Hole size (in.)
16
17
19
20
*Markof Schlumberger
© Schlumberger
Purpose
This chart is used to provide a correction that is subtracted from
the borehole-corrected gamma ray from the arcVISION900 9-in. tool.
Environmental corrections for mud weight and bit size are already
applied to the gamma ray presented on the logs.
Description
This chart is for illustrative purposes only. The indicated correction
is already applied on the gamma ray log.
To determine the correction that was applied to the log output,
enter the chart with the borehole size on the x-axis and move upward
to intersect the downhole mud weight. From the intersection point
move horizontally left to read the correction curve in gAPI units that
was subtracted from the borehole-corrected data.
Back to Contents
45
Gamma Ray— LWD
Schlumberger
EcoScope* Integrated LWD Gamma Ray — 6.75-in. Tool
Borehole Correction for Open Hole
GR-27
3.00
2.75
2.50
2.25
2.00
Correction , jr
factor
1.50
1.25
1.00
0.75
0.50
25-in
.,--
.---
.---
-"*
^ _
..--
---'
,---
_12
bit
_^_
----
.,—
10.625-in. bit
— 1 1
9.875-in. bit
1
_J
.75-in. bit—
i.5-in. bit
!
*Markof Schlumberger
© Schlumberger
9 10 11 12 13 14 15 16 17 18 19
Mud weight (Ibm/gal)
Purpose
This chart is used to provide a correction factor for gamma ray
values measured with the EcoScope 6.75-in. Integrated LWD tool.
These environmental corrections for mud weight and bit size are
normally already applied to the gamma ray presented on the field
logs.
Description
Enter the chart with the mud weight on the x-axis and move upward
to intersect the appropriate bit size. Interpolate between lines as
necessaiy. At the intersection point, move horizontally left to the
y-axis to read the appropriate correction factor that the EcoScope
6.75-in. gamma ray value was multiplied by to obtain the corrected
gamma ray value in gAPI units.
46
Back to Contents
Gamma Ray— LWD
EcoScope* Integrated LWD Gamma Ray — 6.75-in. Tool
Potassium Correction for Open Hole
Schlumberger
GR-28
50
45
40
35
30
Correction
subtracted
for5-wt% 25
potassium
(gAPI)
20
15
10
5
,,---
.---''"
M ppg"
---"' ,,.
_,,---'
_---"""
„. *•**
16
18 ppg''
D P g-
__,-''"
--'"''
,,'*
- ,-.-*" ^*"
^-*"
-' 14pp
g"" ^
+ '* ^.
-''''.---'
';;;::>
10
^I2ppg^
ppg"
•'^--''',
-**"*''" -~0~~~~'
- 8.3 ppg
^^~ — "
8.5 9.0 9.5 10.0 10.5 11.0 11.5 12.0 12.5 13.0
Hole size (in.)
*Markof Schlumberger
© Schlumberger
Purpose
This chart is used to illustrate the potassium correction that is sub-
tracted from the borehole-corrected gamma ray from the EcoScope
6.75-in. Integrated LWD tool. Environmental corrections for mud
weight, bit size, and potassium are normally already applied to the
gamma ray presented on the field logs.
Description
This chart is for illustrative purposes only. The indicated correction
is already applied on the gamma ray log. The chart shows the correc-
tion for a typical 5-wt% potassium concentration.
To determine the correction that was applied to the log output,
enter the chart with the borehole size on the x-axis and move upward
to intersect the downhole mud weight. From the intersection point
move horizontally left to read the correction curve in gAPI units that
was subtracted from the borehole-corrected data.
Back to Contents
47
Spontaneous Potential — Wireline
Rweq Determination from Essp
Schlumberger
Purpose
This chart and nomograph are used to calculate the equivalent for-
mation water resistivity (R W eq) from the static spontaneous potential
(Essp) measured in clean formations. The value of R weq is used in
Chart SP-2 to determine the resistivity of the formation water (R w ).
R w is used in Archie's water saturation equation.
Description
Enter the chart with Essp in millivolts on the x-axis and move
upward to intersect the appropriate temperature line. From the
intersection point move horizontally to intersect the right y-axis for
Rmfeq/Rweq. From this point, draw a straight line through the equiva-
lent mud filtrate resistivity (Rmfeq) point on the Rmf eq nomograph to
intersect the value of R we q on the far-right nomograph.
The spontaneous potential (SP) reading corrected for the effect
of bed thickness (Espcoi) from Chart SP-4 can be substituted for Essp-
Example
First determine the value of Rmfe q :
■ If Rmf at 75°F is greater than 0.1 ohm-m, correct Rmf
to the formation temperature by using Chart Gen-6,
and use Rmfeq = 0.85Rmf.
■ If Rmf at 75°F is less than 0. 1 ohm-m, use Chart SP-2
to derive a value of Rmfeq at formation temperature.
Given: Essp = -100 mV at 250°F and resistivity of the mud
filtrate (Rmf) = 0.7 ohm-m at 100°F, converted to 0.33
at 250°F.
Find: R weq at 250°F.
Answer: Rmf eq = 0.85Rmf = 0.S
xO.S
: 0.28 ohm-m.
Draw a straight line from the point on the Rmfeq/Rweq line
that corresponds to the intersection of Essp = -100 mV
and the interpolated 250°F temperature curve through
the value of 0.28 ohm-m on the Rmfeq line to the R W eq line
to determine that the value of R weq is 0.025 ohm-m.
The value of Rmfeq/Rweq can also be determined from the
equation
ESSP = K c log (Rmfeq/Rweq),
where K c is the electrochemical spontaneous potential
coefficient:
K c = 61 + (0.133 xTemp°F)
K c = 65 + (0.24 x Temp°C).
48
Back to Contents
Spontaneous Potential — Wireline
Rweq Determination from Essp
Schlumberger
SP-1
(former SP-1)
0.3
0.4
0.5
0.6
F
mfe
q/ n we q
0.3
R
(oh
feq
n-m)
01
weq
n-m)
_ 0.001
L 0.005
1 0.01
1 0.02
1 0.05
Z 0.1
L 0.2
L 0.5
Z 1.0
L 2.0
. 0.4
R
--
0.6 (ohr
0.8
1
2
1111111111111111
1 0.8
11 1
. 0.02
I 0.04
: o.o6
L 0.1
. 0.2
~ 0.4
: o.6
1 1
. 2
\ 4
: 6
i 10
. 20
! 40
: 60
I 100
2
3
==
EE3^S^=
-■
R mf /R w 4
5
il
: ~~r|*tVS^
EEEEEEEEEEEEEEEE
E
EE
I_ 4
3J E^ S
6
==
E_6
8
10
8
ll|l|l
L io
^ fl
J A
j ^ V V
\
w s^ ^ H ^ !s ^
r
\\ \ V k c-
i
1 ■ <fc V '^ ^
.CH
"
20
i il I ". "k^r
^.CK
T 40 A
,- .
\ Vr % ^ V£>\
■M
Formation :
temperature ee
" ^ .= " &<£&&\t°3i
. \\o'\ffo (\(T' w-
30
---m^Yi' Prrc %"
jm
40
1
\Wx\i InT
z-
5U 1 l_Lj_l L-L-L-
+50 (
© Schlumberger
) -50
Static spontaneous p
1 X \ , 1 IV. I n I i«
-100 -150 -200 :
otential, E SSP (mV) -
< ►
Back to Contents
49
Spontaneous Potential — Wireline
Rweq versus R w and Formation Temperature
Schlumberger
SP-2
(customary, former SP-2)
0.001
0.002
0.005
0.01
0.02
''weq *■" ""mfeq
(ohm-m) 0.05 1
0.1
0.2 L
0.5
1.0
2.0
|\ 500° F
t\ 400° F
300° F
0.005
J I i i i i
0.02 0.03
0.1 0.2 0.3
R,„ or FL, (ohm-m)
© Schlumberger
Purpose
This chart is used to convert equivalent water resistivity (R weq ) from
Chart SP-1 to actual water resistivity (R w ). It can also be used to con-
vert the mud nitrate resistivity (Rmf) to the equivalent mud filtrate
resistivity (Rmf eq ) in saline mud. The metric version of this chart is
Chart SP-3 on page 49.
The dashed lines can also be used for gypsum-base mud nitrates.
Example
Given:
Find:
Answer:
Description
The solid lines are used for predominantly NaCl waters. The dashed
lines are approximations for "average" fresh formation waters (for
which the effects of salts other than NaCl become significant).
50
a ► Back to Contents
From Chart SP-1, R weq = 0.025 ohm-m at 250°F in
predominantly NaCl water.
R w at250°F.
Enter the chart at the R we q value on the y-axis and move
horizontally right to intersect the solid 250°F line. From
the intersection point, move down to find the R w value
on the x-axis. R w = 0.03 ohm-m at 250°F.
Spontaneous Potential — Wireline
Rweq versus R w and Formation Temperature
Schlumberger
SP-3
(metric, former SP-2m)
0.001
0.002
0.005
0.01
0.02
■■weq *-" ''mfeq
(ohm-m) 0-05
0.1
0.2
0.5
1.0
20
r
\
\
- 250°C
_200°C
\ 1 Rf
)°C
100°C
\
\
I
k
\
] \
\
\ V
_75°C
A
V-
\\ \
T7
\
\ \
\ s
V
50°C
\
1
\
25 c
U
\
\ Saturation
VX-
^
v/N
r
^t
^
v.
«»
.^
N
• ,
--
^
^^
<N\
V
X
"--.^
^
**" 2SO°r
Si
^
' — ■
i y c
m
>,
•
s
^^
» ,
20o°n
^
V
\
s
*
^
*J i L
S
V
N
*»- *»
" ISq^p
-
s
>
•v
N
^
^7/J,
s
>
'^{ L °°n
/I
s v
^ ?s °c
\
<5
>
s^
(9
X.
. \ u C ■
%
PL
■
i i i i i i i . i i >i
o.oc
© Schlumberger
5 0.01 0.02 0.03 0.05 0.1 0.2 0.3 0.5 1.0 2 3 4
R w or R mf (ohm-m)
Purpose
This chart is the metric version of Chart SP-2 for converting equiva-
lent water resistivity (R weq ) from Chart SP-1 to actual water resistiv-
ity (Rw). It can also be used to convert the mud filtrate resistivity (Rmf)
to the equivalent mud filtrate resistivity (Rmfeq) in saline mud.
Description
The solid lines are used for predominantly NaCl waters. The dashed
lines are approximations for "average" fresh formation waters
(for which the effects of salts other than NaCl become significant).
The dashed lines can also be used for gypsum-base mud nitrates.
Example
Given: From Chart SP-1, R weq = 0.025 ohm-m at 121°C in
predominantly NaCl water.
Find: R w atl21°C.
Answer: R w = 0.03 ohm-m at 12 FC.
< ►
Back to Contents
Spontaneous Potential — Wireline
Bed Thickness Correction — Open Hole
Schlumberger
Purpose
Chart SP-4 is used to correct the SP reading from the well log for
the effect of bed thickness. Generally, water sands greater than
20 ft in thickness require no or only a small correction.
Description
Chart SP-4 incorporates correction factors for a number of condi-
tions that can affect the value of the SP in water sands.
The appropriate chart is selected on the basis of resistivity, inva-
sion, hole diameter, and bed thickness. First, select the row of charts
with the most appropriate value of the ratio of the resistivity of shale
(R s ) to the resistivity of mud (R m ). On that row, select a chart for no
invasion or for invasion for which the ratio of the diameter of invasion
to the diameter of the wellbore (di/dh) is 5. Enter the x-axis with
the value of the ratio of bed thickness to wellbore diameter (h/dh).
Move upward to intersect the appropriate curve of the ratio of the
true formation resistivity to the resistivity of the mud (Rt/R m ) for
no invasion or the ratio of the resistivity of the flushed zone to the
resistivity of the mud (R X o/Rm) for invaded zones, interpolating
between the curves as necessaiy. Read the ratio of the SP read from
the log to the corrected SP (Esp/Espcor) on the y-axis for the point of
intersection. Calculate Espcor = Esp/(Esp/Esp C oi). The value of Egpcor
can be used in Chart SP-1 for Essp.
52
Back to Contents
Spontaneous Potential — Wireline
Bed Thickness Correction — Open Hole
Schlumberger
SP-4
(former SP-3)
No Invasion
Invasion, di/d h = 5
EsP' ^sPcor
1.0
0.8
0.6
0.4
0.2
10
s.
N
'20
\
50
\
100
\
200
R,/R m /
40 30 20 15 10 7.5 5
h/d h
EsP' EsPcor
1.0
0.8
0.6
0.4
0.2
^
"10
s
20
\
\
RO
\
100
200,
R,/R m -
500 .
40 30 20 15 10 7.5 5
h/d h
:20
EsP' Espcor
1.0
0.8
0.6
0.4
0.2
T-2:
jo N
20
\
50
\
100 ,
200
R,/R m —
,000
R.„ = 0.2R,
I 1.0
0.8
0.6
0.4
0.2
?>
\
^
s
"•^
X
\\
•0.2
V
\
'or
\
>,\
\
^
\
\
>\
\ s
20\
50 N
R xo/ R m —-
• \
100 ■
1.0
0.8
0.6
0.4
0.2
,0.5
1,\
\ N
\ N
&
20 A
100
200 .
Rxo/ R m "
1.0
0.8
0.6
0.4
0.2
.0.5
10 N
^ \
20 '
\\
50
. \
100
200
Rxo/ R m ^
40 30 20 15 10 7.5 5 40 30 20 15 10 7.5 5
h/d h h/d h
1.0 1.0
40 30 20 15 10 7.5 5
h/d h
0.8
0.6
0.4
0.2
1
1
\
S^
0.2 .
0.5
\\
>
s N
s
\
\
s\
\
^
>
s\
\
5—
\
\
'10 s
20
'50 N
J 00
200 ■
Rxo/ R m —
rj0.5.
08
06
10
20
04
;\
50
0?
\\
100
•» s
-200
'R00 '
R xo/ R m
1.0
0.8
0.6
0.4
0.2
t
10
20
\
50
100
200
s
500 ,
R xo/ R m -^
40 30 20 15 10 7.5 5 40 30 20 15 10 7.5 5
h/d h h/d h
1.0 1.0
40 30 20 15 10 7.5 5
h/d h
08
-1 \
2 \
06
5
\
10
04
\
20
\
09
^50
S 100 N
200 '
500 '.
Rxo/Rm^
0.8
0.4
0.2
"2=!;
5 \
10
20
\
s
50
\
s
100
>
200
•500 .
,000
R xo/ R m^
1.0
0.8
0.6
0.4
0.2
r 4:
10^"
20 N
\
'50
\
l ioo
\
200
500
Rxo/Rn,- 1 ,.™-
40 30 20 15 10 7.5 5
h/d h
40 30 20 15 10 7.5 5 40 30 20 15 10 7.5 5
h/d h h/d h
40 30 20 15 10 7.5 5
h/d h
5 Schlumberger
< ►
Back to Contents
53
Spontaneous Potential — Wireline
Bed Thickness Correction — Open Hole (Empirical)
Schlumberger
SP-5
(customary, former SP-4)
100
8-in. Hole; 3 3 /s-in. Tool, Centered
1.0
i
d s (in.)
^v
90
V (
b
Ri
80
i\
^
R m
\*
<§V
70
60
*
5
_1.5
X
j
^SSP
Correction
(%)
factor
50
20
_2.0
40
50
12.5
Z3.0
30
100
_3.5
_4.0
20
"
200
1 5.0
v_
7
] 50
4
D 3
D 20 15 10 9 8 7 6 !
i 4 :
Bed thickness, h (ft)
© Schlumberger
Purpose
This chart is used to provide an empirical correction to the SP for
the effects of invasion and bed thickness. The correction was obtained
by averaging a series of thin-bed corrections in Reference 4. The
resulting value of static spontaneous potential (Essp) can be used
in Chart SP-1.
Description
This chart considers bed thickness (h) as a variable, and the ratio of
the resistivity of the invaded zone to the resistivity of the mud (Ri/R m )
and the diameter of invasion (dj) as parameters of fixed value. The
borehole diameter is fixed at 8 in. and the tool size at 3% in.
To obtain the correction factor, enter the chart on the x-axis with
the value of h. Move upward to the appropriate d; curve for the range
of Ri/Rm- The correction factor on the y-axis corresponding to the
intersection point is multiplied by the SP from the log to obtain the
corrected SP.
54
Back to Contents
Spontaneous Potential — Wireline
Bed Thickness Correction — Open Hole (Empirical)
Schlumberger
SP-6
(metric, former SP-4m)
200-mm Hole; 86-mm Tool, Centered
'-SSP
(%)
1.0
.1.5
Correction
factor
.2.0
.2.5
.3.0
.3.5
.4.0
.5.0
20 15 10
5 3 2
Bed thickness, h (m)
© Schlumberger
Purpose
This chart is the metric version of Chart SP-5 for providing an empir-
ical correction to the SP for the effects of invasion and bed thick-
ness. The correction was obtained by averaging a series of thin-bed
corrections in Reference 4. The resulting value of Essp can be used
in Chart SP-1.
Description
This chart considers bed thickness (h) as a variable, and Ri/R m and
di as parameters of fixed value. The borehole diameter is fixed at
203 mm and the tool size at 86 mm.
Back to Contents
55
Density — Wireline, LWD
Porosity Effect on Photoelectric Cross Section
Schlumberger
Dens-1
Pe k
*- <
1 2 3 4 5 6 0.5 0.4 0.3 0.2 0.1
\ 1 Water' Gas \
Quartz Dolomite Calcite
I I I
Porosity Effect on Pe
Matrix
<t>,
100% H 2
100% CH 4
Quartz
0.00
1.81
1.81
0.35
1.54
1.76
Calcite
0.00
5.08
5.08
0.35
4.23
4.96
Dolomite
0.00
3.14
3.14
0.35
2.66
3.07
Specific
gravity
1.00
0.10
) Schlumberger
Purpose
This chart and accompanying table illustrate the effect that porosity,
matrix, formation water, and methane (CH4) have on the recorded
photoelectric cross section (Pe).
Description
The table lists the data from which the chart was made. As the
porosity increases the effect is greater for each mineral. Calcite has
the largest effect in the presence of gas or water as the porosity
increases.
Enter the chart with the total porosity (§ t ) from the log and move
downward to intersect the angled line. From this point move
to the left and intersect the line representing the appropriate matrix
material: quartz, dolomite, or calcite minerals. From this intersection
move upward to read the correct Pe.
56
Back to Contents
Density — Wireline, LWD
Apparent Log Density to True Bulk Density
Schlumberger
Dens-2
Pb-Plog
(g/cm 3 )
0.14
0.12
0.10
0.08
0.06
0.04
0.02
-0.02
-0.04
Salt(NaCI)
Sylvite (KCI)
Magnesium
<(> = 40%
Add correction
from y-axis to p| 0g
to obtain true
bulk density, p b
Aluminum"
cf» = 40%
Limestone + water
Dolomite + water
Gypsum (
J
© Schlumberger
p to g(g/cm 3 :
Purpose
This chart is used to determine the true bulk density (pb) from the
"apparent" recorded log value (piog).
Description
Enter the chart with the log density reading on the x-axis and move
upward to intersect the mineral line that best represents the forma-
tion. At this point, move horizontally left to read the value to be added
to the log density. The individual mineral points reflect the log-derived
density and the correction factor to be added or subtracted from the
log value to obtain the true density of that mineral.
The long diagonal lines representing zero porosity at the lower
right and 40% porosity at the upper left are for dry gas in the forma-
tion. The three points at the lower right of the diagonal lines rep-
resent zero dry gas in the formation and are the endpoints for
sandstone, limestone, and dolomite with water in the pores. This
shows that there is a slight correction for water-filled formations
from the log density value.
Example
Given:
Find:
Answer:
Log density = 2.40 g/cm 3 in a sandstone formation
(dry gas).
Corrected bulk density.
Enter the x-axis at 2.4 g/cm 3 and move upward to inter-
sect the sandstone line. The correction from the y-axis is
0.02 g/cm 3 . The correction value is added to the log den-
sity to obtain the true value of the bulk density:
2.40 + 0.02 = 2.42 g/cm 3 .
Back to Contents
57
Neutron — Wireline
Schlumberger
Dual-Spacing Compensated Neutron Tool Charts
This section contains interpretation charts to cover developments in
compensated neutron tool (CNT) porosity transforms, environmental
corrections, and porosity and lithology determination.
CSU* software (versions CP-30 and later) and MAXIS* software
compute three thermal porosities: NPHI, TNPH, and NPOR.
NPHI is the "classic NPHI," computed from instantaneous near
and far count rates, using "Mod-8" ratio-to-porosity transform with
a caliper correction.
TNPH is computed from deadtime-corrected, depth- and
resolution-matched count rates, using an improved ratio-to-porosity
transform and performing a complete set of environmental corrections
in real time. These corrections may be turned on or off by the field
engineer at the wellsite. For more information see Reference 32.
NPOR is computed from the near-detector count rate and TNPH
to give an enhanced resolution porosity. The accuracy of NPOR is
equivalent to the accuracy of TNPH if the environmental effects on
the near detector change less rapidly than the formation porosity.
For more information on enhanced resolution processing, see
Reference 35.
Cased hole CNT logs are recorded on NPHI, computed from
instantaneous near and far count rates, with a cased hole ratio-to-
porosity transform.
Using the Neutron Correction Charts
For logs labeled NPHI:
1. Enter Chart Neu-5 with NPHI and caliper reading to convert to
uncorrected neutron porosity.
2. Enter Charts Neu-1 and Neu-3 to obtain corrections for each
environmental effect. Corrections are summed with the uncor-
rected porosity to give a corrected value.
3. Use crossplot Charts Por-11 and Por-12 for porosity and lithology
determination.
For logs labeled TNPH or NPOR, the CSU wellsite surface instru-
mentation and MAXIS software have applied environmental correc-
tions as indicated on the log heading. If the CSU and MAXIS
software has applied all corrections, TNPH or NPOR can be used
directly with the crossplot charts. In this case:
1. Use crossplot Charts Por-11 and Por-12 to determine porosity
and lithology.
58
Back to Contents
Neutron — Wireline
Compensated Neutron Tool
Environmental Correction — Open Hole
Schlumberger
Purpose
Chart Neu-1 is used to correct the compensated neutron log porosity
index if the caliper correction was not applied. If the caliper correc-
tion is applied, it must be "backed out" to use this chart.
Description
This chart is used only if the caliper correction was not applied
to the logged data. The parameter section of the log heading lists
whether correction was applied.
Example 1: Backed-Out Correction of TNPH Porosity
Given: Thermal neutron porosity (TNPH) from the log = 32 p.u.
(apparent limestone units) and borehole size = 12 in.
Find: Uncorrected TNPH with the correction backed out.
Answer: Enter the top chart for actual borehole size at the inter-
section point of the standard conditions 8-in. horizontal
line and 32 p.u. on the scale above the chart.
From this point, follow the closest trend line to intersect
the 12-in. line for the borehole size.
The intersection is the uncorrected TNPH value of 34 p.u.
To use the uncorrected value on Chart Neu-1, draw a ver-
tical line from this intersection through the remainder of
the charts, as shown by the red line.
Example 2: Environmentally Corrected THPH
Given: Neutron porosity of 32 p.u. (apparent limestone units),
without environmental correction, 12-in. borehole, Vi-m,
thick mudcake, 100,000-ppm borehole salinity, 11-lbm/gal
natural mud weight (water-base mud [WBM]), 150°F
borehole temperature, 5,000-psi pressure (WBM), and
100,000-ppm formation salinity.
Find: Environmentally corrected TNPH porosity.
Answer: If there is standoff (which is not uncommon), use Chart
Neu-3. Then use Chart Neu-1 by drawing a vertical line
through the charts for the previously determined
backed-out (uncorrected) 34-p.u. neutron porosity
value.
On each environmental correction chart, enter the y-axis
at the given value and move horizontally left to intersect
the porosity value vertical line.
For example, on the mudcake thickness chart the line
extends from l A in. on the y-axis.
At the intersection point, move parallel to the closest
blue trend line to intersect the standard conditions, as
indicated by the bullet.
The point of intersection with the standard conditions
for the chart is the value of porosity corrected for the
particular environment. The change in porosity value
(either positive or negative) is summed for the charts
and referred to as delta porosity (A(|>).
The A(|) net correction applied to the uncorrected log neutron
porosity is listed in the table for the two examples.
CNT Neutron Porosity Correction Examples
Correction
Example 1
Example 2
A(j)
Log porosity
32 p.u.
Borehole size
12 in.
-2
Mudcake thickness
V,m.
Borehole salinity
100,000 ppm
+1
Mud weight
11 Ibm/gal
+2
Borehole temperature
150°F
+4
Wellbore pressure
5,000 psi
-1
Formation salinity
100,000 ppm
-3
Standoff (from Chart Neu-3)
1 in.
-4
Net environmental correction
-1
Backed-out corrected porosity
34 p.u.
Environmentally corrected porosity
33 p.u.
Net correction
-3
Backed-out, environmentally corrected porosity
31 p.u.
< ►
Back to Contents
continued on next page
59
Neutron — Wireline
Compensated Neutron Tool
Environmental Correction — Open Hole
Schlumberger
Neu-1
(customary, former Por-14c)
Neutron log porosity index (appa
10 20
rent limestone porosity in p.u.)
30 40 50
71
20 I / T 7 _
Actual borehole size 16 / / / S ,/
(in) _i2-_^i y y\ y ,y
y i. ' ^' ^ y ^?
s / ~7 2 TP* ~2* '
y "JZZ^ „*< ^ - .
4 y _y y%_ ^ _«<>*_
1.0
Mudcake thickness \j 1 1 1 J
(m) t---J----t---t---t---i
t \ X X
t ___1 I Zt t [
t 1___^ .
?50
\ X X X X
- X X- X~ X X -
Borehole salinity \ \ \ i \
X X \ v a
11 ,000 x ppml T \ t _t t.
X J 3 \ \
X ^ \ a X
$ [ ' \ v \
± ± \ _L \
. A V J a > .
u
12 i r t t r _
. \ T- \ T V _
M | _1J A I L _L_ J
.__x i___ \ \ .% ,
Natural -£■ j + ¥ 1 T
X — ^ v a - - v
9 _ _f_ ' 1 A - ■ A-
. A - . & _ £ . _ \ _ \
... r 4 1 \ i 'i
__. _3__ __ ^_. 3 L _- _^__ ._> .
Mud weight
(Ihrn/qql) 18
16 I I f L V-
' X V- X~ X \~
R.rito 14 4 4 4X1
\ \ X \
Bante 1^ j 1 A T
X i v \
10 r i ~v V I
A \ X \ \
8 t ± ± ± i
. ± Jl. ^ J _ .
)0 "I \ V X ^T S ^
N S> «^. ^^ "^^^
Borehole temperature \ \ \ \. V S.
S S^ s s^^ S ^^ ^^ v
CF) A S___X— -V— XI'
»< N <v N\ "^^^ v>, ->
a \ i 4 i
"J T "s"^
50 \ — h l- ^C" -=5 ^ -is
: - ^^ ^ S^b, - ^ : •
n
Pressure I : / • / •'/
j~'' / ••*? /~ .v""
(1,000 xpsi) tl 1 ■' t -'7
yf /.. - 2 Z ■■■'' y -/
P t^ /-•■' 4 -•■'
7 .••> 2 Z - '' y .•••'"' /
Water-hasp mud I- / ■* / 1 -•' / 1 ••'
r '''j ^''"? ••t .y % "' %
Oil hn^n muri 1 f " <"\ '••' /
\~'\ Tv^y /■•■■' /! /.
?fif)
/ ...
r i r r
" \ A" X A \ "
Limestone L L _) \_
Y % X V
formatinn salinity / / / /
.__/_ 1 ±11
(1000 v DDm)' / /' y /
"/ "& J / JL
Ii,uuuxppm| o tL y y y *
y ,<y\ y y /
10 20
© Schlumberger
30 40 50
• Standard conditions
60
< ►
Back to Contents
Neutron — Wireline
Compensated Neutron Tool
Environmental Correction — Open Hole
Schlumberger
Neu-2
(metric, former Por-14cm)
Neutron log porosity index (apparent limestone porosity)
10 20 30 40 50
I I I I I I
600
500
Actual borehole size 400
(mm) 300
200
100
ludcake thickness
(mm)
Borehole salinity
(g/kg)
25
12.5
250
1.5
Mud density 1 -°
(g/cm 3 ) 2.0
149
121
Borehole temperature 93
(°C) 66
38
10
□ 172
Pressure ,no
(MPa) ]j£
Water-base mud °?
34
Oil-base mud J!
250
Limestone
formation salinity
(g/kg)
LLim IXXX
/ / / L l_l_l\
y v T
I \ A- T \
\
\
4 4 V
t L L V V
\
\
4 4 4
V V \ v f
\
\
4 4 4
4^444
\
\
1.0 _ 1 ± ± _
± \ \ \ \_
\
l
a
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
10 20 30 40 50
• Standard conditions
© Schlumberger
Purpose
This chart is the metric version of Chart Neu-1 for correcting the
compensated neutron tool porosity index.
< ►
Back to Contents
Neutron — Wireline
Compensated Neutron Tool
Standoff Correction — Open Hole
Schlumberger
Purpose
Chart Neu-3 is used to determine the porosity change caused by
standoff to the uncorrected thermal neutron porosity TNPH from
Chart Neu-1.
Description
Enter the appropriate borehole size chart at the estimated neutron
tool standoff on the y-axis. Move horizontally to intersect the uncor-
rected porosity. At the intersection point, move along the closest
trend line to the standard conditions line defined by the bullet to
the right of the chart. This point is the porosity value corrected for
tool standoff. The difference between the standoff-corrected porosity
and the uncorrected porosity is the correction itself.
Example
Given:
Find:
Answer:
TNPH = 34 p.u., borehole size = 12 in., and
standoff =0.5 in.
Porosity corrected for standoff.
Draw a vertical line from the uncorrected neutron log
porosity of 34 p.u. Enter the 12-in. borehole chart at
0.5-in. standoff and move horizontally right to intersect
the vertical porosity line. From the point of intersection
move parallel to the closest trend line to intersect the
standard conditions line (standoff = in.). The standoff-
corrected porosity is 32 p.u. The correction is -2 p.u.
62
Back to Contents
Neutron — Wireline
Compensated Neutron Tool
Standoff Correction — Open Hole
Schlumberger
Neu-3
(customary, former Por-14d)
Actual C
borehole size
Neutron log porosity index (apparent limestone
10 20 30
Dorosity in p.u.)
40 50
6 in.
i
1
1
j
<
/
J
J
J
1
'
'
'
'
/
,
8 in. 1
I
j
1
1
,
1
i
1
/
i
/
/
j
f
/
J
/
t
/
7
/
/
/
/
/
y
y
/
/
/
/
/
f
/
y
/
y
•
/
/
/
/
/
/
'
f
/
y
y
y
/
/
r
10 in.
I
1
i
i
i
i
1
/
/
i
1
j
J
/
J
/
/
J
/
/
/
V
/
/
/
/
/
/
/
/
/
/
y
/
v
s
y
•
s
y
/
/
/
y
/
y
y
y
y
y
y
•
/
/
/
/
z
/
s
y
y
y
X
y
y
y
y
/
/
/
y
y
y
y
y
/
z
/
,
4
3
12 in. 2
1
i
i
i_
i
1
j
1
y
'
/
J
)
/
/
/
/
/
/
/
/
/
y
y
y
/
/
/
/
/
y
y
y
y
y
y-
y
y
y
y
y
y
S
y
y
y
y
y
y
y
y
y
y
y
yy
y
**
y
y
y*
y
y
y
y
y
y
y
**
y
y
y^
y
y
s
y
y
y
-*
y
y
y
y'L
^y
y
7
Standoff g
(in.)
5
18 in. 4
3
2
1
•
10
9
8
7
6
24 in.
5
4
3
2
1
^
c
© Schlumberger
1 1 I 111
10 20 30
1
40 \
• Standard conditions
1
)0
< ►
Back to Contents
63
Neutron — Wireline
Compensated Neutron Tool
Standoff Correction — Open Hole
Schlumberger
Neu-4
(metric, former Por-14dm)
Actual C
borehole size
Neutron log porosity index (apparent limestone porosity)
10 20 30 40 50
25
150 mm
J
1
1
1
\
/
J
J
J
1
1
1
■
'
/
'
/
'
,
(
1
50
200 mm 25
I
)
I
1
,
1
1
•
J
/
J
f
t
1
j
'
1
J
I
1
/
/
/
/
/
/
/
/
/
/
f
/
/
/
f
/
y
/
y
/
y
/
/
/
r
/
'
r
/
y
y
y
/
<
!
75
250 mm
25
1
/
J
/
1
/
4
/
1
1
/
/
/
I
/
/
/
J
/
J
/
/
/
/
y
/
/
/
7
/
/
/
t
/
s
y
y
y
/
y
/
/
/
/
/
/
y
y
y
y
S
y
y
/
s
/
/
7
/
s
y
y
y
y
y
y
s
y
/
/
'
y
y
y
y
/
/
f
100
75
300 mm 50
25
1
1
1
J
/
1
I
1
y
1
/
/
/
/
/
/
/
/
/
/
/
/
/
y
y
s
y
y
/
/
y
y
y
y
y
y
y
y
y
y
y
S
y
y
y
^y
y
s
s
s
y
y
**
**
^
y
y
S>
y
y
s
y
y
y
•*■"
**
*•
y
y
s
y
/
y
y
**■
s'
y
y
y
2T
/
175
Standoff q 5Q
(mm)
125
450 mm 10 °
75
50
25
-1 •
250
225
200
175
150
600 mm ^
100
75
50
25
(
© Schlumberger
1 1 1 1
) 10 20 30 40 i
• Standard conditions
1
so
Purpose
This chart is the metric version of Chart Neu-3 for determining the
porosity change caused by standoff.
64
< ► Back to Contents
Neutron — Wireline
Compensated Neutron Tool
Conversion of NPHI to TNPH— Open Hole
Schlumberger
Neu-5
(former Por-14e)
NPHI porosity index (apparent limestone porosity in p.u.)
5 10 20 30 40 50
.... 1 1 1 1 1 1
24
20
Borehole size '°
M »
4
7
/
/
'
/
/
/
/
/
/
/
/
/
/
•
/
t
/
/
/
>
/
/
/
/
/
/
/
/
/
/
f
/
/
/
/
/
/
*-
f"
y
--
0-
y
-"■
--
y
«•
**•
s
^-
<-"
>
,''
*"'
+*'
*>*'
© Schlumberger
10
TNPH porosity index (
20 30 40 50
apparent limestone porosity in p.u.)
• Standard conditions
Purpose
This chart is used to determine the porosity change caused by the
borehole size to the neutron porosity NPHI and convert the porosity
to thermal neutron porosity (TNPH). This chart corrects NPHI only
for the borehole sizes that differ from the standard condition of 8 in.
Refer to Chart Neu-1 to complete the environmental corrections for
the TPNH value obtained.
Description
Enter the scale at the top of the chart with the NPHI porosity.
Example
Given:
Find:
Answer:
NPHI porosity = 12.5% and borehole size = 16 in.
Porosity correction for nonstandard borehole size.
Enter the chart with the uncorrected porosity value
of 12.5 at the scale at the top. Move down vertically
to intersect the standard conditions line indicated by
the bullet to the right. Enter the chart on the y-axis with
the actual borehole size at the zone of interest and move
horizontally right across the chart.
At the point of intersection of the vertical line and the
standard conditions line, move parallel to the closest
trend line to intersect the actual borehole size line.
At that intersection point move vertically down to the
bottom scale to determine the TNPH porosity corrected
only for borehole size. This value is also used to deter-
mine the change in porosity as a result of tool standoff.
TNPH = 12.5 + 5 = 17.5 p.u.
Back to Contents
65
Neutron — Wireline
Compensated Neutron Tool
Formation £ Correction for Environmentally Corrected TNPH — Open Hole
Schlumberger
Purpose
This chart is used to further correct the environmentally corrected
TNPH porosity from Chart Neu-1 for the effect of the total forma-
tion capture cross section, or sigma (£), of the formation of inter-
est. This correction is applied after all environmental corrections
determined with Chart Neu-1 have been applied.
Description
Enter the chart with £ for the appropriate formation along the y-axis
and the corrected TNPH porosity along the x-axis. Where the lines
drawn from these points intersect, move parallel to the closest trend
line to intersect the appropriate fresh- or saltwater line to read the
corrected porosity.
The chart at the bottom of the page is used to correct the £-
corrected porosity for salt displacement if the formation £ is due to
salinity. However, this correction is not made if the borehole salinity
correction from Chart Neu-1 has been applied.
Example
Given:
Find:
Answer:
Corrected TNPH from Chart Neu-1 = 38 p.u., £ of the
sandstone formation = 33 c.u., and formation salinity =
150,000 ppm (indicating a freshwater formation).
TNPH porosity corrected with Chart Neu-1 and for £ of
the formation.
Enter the appropriate chart with the £ value on the y-axis
and the corrected TNPH value on the x-axis. At the inter-
section of the sigma and porosity lines, parallel the clos-
est trend line to intersect the freshwater line. (If the
water in the formation is salty, the 250,000-ppm line
should be used.)
Move straight down from the intersection point to the
formation salinity chart at the bottom.
From the point where the straight line intersects the top
of the salinity correction chart, parallel the closest trend
line to intersect the formation salinity line.
Draw a vertical line to the bottom scale to read the cor-
rected formation sigma TNPH porosity, which is 35 p.u.
66
Back to Contents
Neutron — Wireline
Compensated Neutron Tool
Formation £ Correction for Environmentally Corrected TNPH — Open Hole
Schlumberger
Neu-6
(former Por-1 6)
Neutron log porosity index
10 20 30
1 1 1
40 50
i 1
70
60
Sandstone formation grj
Formation! (c.u.)
40
'
.
1
'
'
-
!'
1
i
„ "
'
/
/
-'"J-
i
/
/
t
j.
i
/
r
30
20
Fresh water
i
'
/
/
/
/
/ /
' 1
/
.?
/
J
/
-/ -
1
r
/
/
/
/
/
/
250,000- ppm water 10
4-
■s
/.
/
— ',
S
/
/
'U.
->
±
*i—
70
60
Limestone formation g n
Formation! (c.u.)
40
30
Freshwater
^
-
'
"
,
^'
I
J
/
/
f
4
,
—■
/
250,000-ppm water 10
±~
^—
—r
70
60
Dolomite formation eg
Formation! (c.u.)
40
30
Freshwater
1
j
i
j
'
„
'
,
f j
'
/
/
-' "j.
/
/
/
1
r
/
/
1
i
i
J
—
J-
^
-
fir
/
**
*■— 3
**z.
Formation salinity 100
(1,000 x ppm)
250
\
V
V
\
L
V
\
\
\
\
5
v.
'
\
V
>
v
V
\
s S
\
v
\
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s
V,
\
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\
\
\
V
\
\
v
s
\
(
© Schlumberger
i i i ||m
) 10 20 30
1 ' ' 1 1 1
40 50
< ►
Back to Contents
67
Neutron — Wireline
Compensated Neutron Tool
Mineral I Correction for Environmentally Corrected TNPH — Open Hole
Schlumberger
Purpose
This chart is used to further correct the environmentally corrected
TNPH porosity from Chart Neu-1 for the effect of the mineral sigma
(£). This correction is applied after all environmental corrections
determined with Chart Neu-1 have been applied.
Description
Enter the chart for the formation type with the mineral £ value along
the y-axis and the Chart Neu-1 corrected TNPH porosity along the
x-axis. Where lines drawn from these points intersect, move parallel to
the closest trend line to intersect the freshwater line to read the
corrected porosity on the scale at the bottom. The choice of chart
depends on the type of mineral in the formation.
Example
Given:
Find:
Answer:
Corrected TNPH from Chart Neu-1 = 38 p.u., sandstone
formation £ = 35 c.u., and formation salinity =
150,000 ppm (indicating a freshwater formation).
TNPH porosity corrected with Chart Neu-1 and for the
mineral £.
At the intersection of the £ and porosity value lines
move parallel to the closest trend line to intersect the
freshwater line. Move straight down to intersect the bot-
tom prosify scale to read the TNPH porosity corrected
for mineral £, which is 33 p.u.
68
Back to Contents
Neutron — Wireline
Compensated Neutron Tool
Mineral I Correction for Environmentally Corrected TNPH — Open Hole
Schlumberger
Neu-7
(former Por-17)
Neutron log porosity index
10 20 30 40 50
70
60
50
40
Sandstone formation
Mineral! (c.u.) 30
20
10
i
7
r
I
'
,
1
'
,
,
f
'
,
r
I
J
/
j
I
1
_J
r
/
t
/
I
/
/
/
/
1
/
/
1
/
y
/
. J
I
]
/
J
r
/
I
1
1
1
/
/
/
_f
/
2
^
/
/
/
f
/
Fresh water
70
60
50
40
Limestone formation
Mineral! (c.u.) 30
20
10
1
/
/
/
\
/
/
\
/
1
/
h
r
f
1
1
f
/
7
/
,
1
I
I
J
1
I
/
/
f-
— y
/
/
*■ —
— ■*■
—**
^
- ~?
7"—
* —
70
60
50
40
Dolomite formation
Mineral! (c.u.) 30
20
10
"T
"I
1
t
'
7
j
f
.
J
.j
±
7
7
,
r
/
j
'
f_
I
I
1
[
,
Y
J
r
1
4
/
t
/
J
/
/
/
/
/
s
/-
4-
Fresh water
(
© Schlumberger
1 1 1 1 1
) 10 20 30 40 50
•* ►
Back to Contents
69
Neutron — Wireline
Compensated Neutron Tool
Fluid £ Correction for Environmentally Corrected TNPH — Open Hole
Schlumberger
Purpose
This chart is used to correct the environmentally corrected TNPH
porosity from Chart Neu-1 for the effect of the fluid sigma (£) in
the formation. This correction is applied after all environmental
corrections determined with Chart Neu-1 have been applied.
Description
Enter the appropriate formation chart with the formation fluid £
value on the y-axis and the Chart Neu-1 corrected TNPH porosity on
the x-axis. Where the lines drawn from these points intersect, move
parallel to the closest trend line to intersect the appropriate fresh-
or saltwater line. If the borehole salinity correction from Chart Neu-1
has not been applied, from this point extend a line down to intersect
the formation salinity chart at the bottom. Move parallel to the
closest trend line to intersect the formation salinity line. Move
straight down to read the corrected porosity on the scale below
the chart.
Example
Given:
Find:
Answer:
Corrected TNPH from Chart Neu-1 = 30 p.u. (without
borehole salinity correction), fluid £ = 80 c.u., fluid
salinity = 150,000 ppm, and sandstone formation.
TNPH corrected with Chart Neu-1 and for fluid £.
At the intersection of the fluid £ and Chart Neu-1
corrected TNPH porosity (30-p.u.) line, move parallel
to the closest trend line to intersect the freshwater line.
From that point go straight down to the formation salinity
correction chart at the bottom.
Move parallel to the closest trend line to intersect the
formation salinity line (150,000 ppm), and then draw a
vertical line to the bottom scale to read the corrected
TNPH value (26 p.u.).
70
Back to Contents
Neutron — Wireline
Compensated Neutron Tool
Fluid £ Correction for Environmentally Corrected TNPH — Open Hole
Schlumberger
Neu-8
(former Por-1 8)
Neutron log porosity index
L
Sandstone formation
Fluid Zlc.u.)
160
140
120
100
80
Fresh water 60
250,000-ppm water ^g
20
160
Limestone formation
Fluid Zlc.u.)
Fresh water
250,000-ppm water »g
20
160
Dolomite formation
Fluid Zlc.u.)
Freshwater
250,000-ppm water 4Q
10
20
30
40
50
I 4 4 T
140 _ . 1 . 1 . A -t- - - - - -
1 t r 1
120 .._.... -t - r — ± ..i ......
1 4 —t 4—4 A
10° t -i t I -i- t t 1 -
4 7 I i -
so _ . _ . I 3 . 7 . . t f_ t_ T_
60 j J 1 1 J 1 J j J
4 t t J I J J t t
40 _ .1.-7 1.1.. f _ 7 . 7_ 7 . .7
- h ■ ? - / 7 7/ / / 7
20 -= 7 7 7 ^ = 7 3 7 V *£ =
I f 4 T 4 T
140 _ _±_ . _ . I . _± - - I . _±_
j -T t i -t t i
120 j. ....... t. _.f _j _ ...t . . d ...
J I i ^ i ^ 4
100 - - 1 -7 -f J - -H- --J - J - - 1
1 i / i j 7 h
80 J 1 I j L L -1 1
1 j f t J j j l t
60 _ . f . z . _7_ /_ _7 . 7 . . Z-. 7 /
iiiJifftt
40 _ 7 . / / _7 . . f _ . / / . / 7 .
f -? / 7 7 / / / 7
20 =f 7 7 7 ^ a z a z ^ 7 =
Formation salinity
(1,000 xppm)
250
^^^^
© Schlumberger
10
20
30
n -1
40
~1
50
< ►
Back to Contents
Neutron — Wireline
Compensated Neutron Tool
Environmental Correction — Cased Hole
Schlumberger
Purpose
This chart is used to obtain the correct porosity from the neutron
porosity index logged with the compensated neutron tool in casing,
where the effects of the borehole size, casing thickness, and cement
sheath thickness influence the true value of formation porosity.
Description
Enter the scale at the top of the chart with a whole-number (not
fractional) porosity value. Draw a straight line vertically through
the three charts representing borehole size, casing thickness, and
cement thickness. Draw a horizontal line on each chart from the
appropriate value on the y-axis. At the intersection point of the verti-
cal line and the horizontal line on each chart proceed to the blue
dashed horizontal line by following the slope of the blue solid lines
on each chart. At that point read the change in porosity index. The
cumulative change in porosity is added to the logged porosity to obtain
the corrected value. As can be seen, the major influences to the casing-
derived porosity are the borehole size and the cement thickness. The
same procedure applies to the metric chart.
The blue dashed lines represent the standard conditions from
which the charts were developed: 8 3 /4-in. open hole, 5'/2-in. 17-lbm
casing, and 1.62-in. annular cement thickness.
The neutron porosity equivalence nomographs at the bottom are
used to convert from the log standard of limestone porosity to poros-
ity for other matrix materials.
The porosity value corrected with Chart Neu-9 is entered into
Chart Neu-1 to provide environmental corrections necessaiy for
determining the correct cased hole porosity value.
Example
Given:
Find:
Answer:
Log porosity index = 27%, borehole diameter = 11 in.,
casing thickness = 0.304 in., and cement thickness =
1.62 in.
Cement thickness is defined as the annular space
between the outside wall of the casing and the borehole
wall. The value is determined by subtracting the casing
outside diameter from the borehole diameter and divid-
ing by 2.
Porosity corrected for borehole size, casing thickness,
and cement thickness.
Draw a vertical line (shown in red) though the three
charts at 27 p.u.
Borehole-diameter correction chart: From the intersec-
tion of the vertical line and the 11-in. borehole-diameter
line (shown in red dashes) move upward along the
curved blue line as shown on the chart.
The porosity is reduced to 26% by -1 p.u.
Casing thickness chart: The porosity index is changed
by 0.3 p.u.
Cement thickness chart: The porosity index is changed
by 0.5 p.u.
The resulting corrected porosity for borehole, casing,
and cement is 27 - 1 + 0.3 + 0.5 = 26.8 p.u.
72
Back to Contents
Neutron — Wireline
Compensated Neutron Tool
Environmental Correction — Cased Hole
Schlumberger
Neu-9
(former Por-14a)
Customary
10 20 30 40 50
Neutron log porosity index I ■ ■ ■ ■ i ■ ■ ■ ■ I ■ ■ ■ ■ i ■ ■ ■ ■ I ■ ■ ■ ■ i ■ ■ ■ ■ I ■ ■ ■ ■ i ■ ■ ■ ■ I ■ ■ ■ ■ i ■ ■ ■ ■ I
(P-u.) 4
6
Diameter of borehole 8
before running casing 10
(in.) 12
Casing thickness (in.) ^
9.5 x \0.2
11.6.. 14 --
Casing
weight
(Ibm/ftl
13.5..
15.1..
17..
20.. 26..
20 -■ 29..
-■ 47..
0.3
40.. 0.4
4'/2 5'/2 7
OD(in.)
0.5
1
Cement thickness
(in.) 2
v
s
s
V
s
^
^.
*v
~>
^
S
s
v.
s,
*v
^
■^.
».
^
8% in.
s
s
s
"
•^
s -
>v
V
■v
^
■ ■-
\
s
s
s
V
■v
S
\
S.
s
S
\
s
s
s
S
S
I
s
v
\
N
s
-1.0
\
\
\
\
3
-\
\
>
^_
\
\
■u
J4
ii
i.
\
y
y
1
I
\
\
\
\
\
i
l
i
L
i
L
1
I
\
\
\
\
\
1
+0.3
\
\
■1
6
I in. "
\
\
\
V
+0.5
Borehole, casing, and cement correction =-1.0 + 0.3 + 0.5
Metric
Neutron log porosity index L
(p.u.) 10()
Diameter of borehole 200
before running casing
(mm)
300
Casing
weight
(kg/m)
Casing thickness (mm) 4CI0
14 r \ 5
17 L 2 1.C-
20
23
25.5..
30.0.
34.5..
30
39
43.
60.
70.
114 140 178 245
ODImm)
Cement thickness
(mm)
7
9
11
13
25
50
75
10
10
20
30
j_I_i
20
30
j_I_i
40
40
50
X
s
-^
s
s
"S
s
s
"s
V
V
^
*%
~s
*•»
-»
^
-*.
^
■^.
S
V
s
N
V
V
V
"V
V
^.
>v
•**.
^
••i
-222 mn
l
S
S
S
s
r-
"N
^
V
s.
V
>*
V
s
V
S
V
s
s
s
\,
>«
v
V
S,
\
\
s
\
\
s
s
S
s
s
\
S
s
1-
s
N
s
s
\
\
\
V
\
\
\
\
\
-7.7 r
r
t-
L-
(-
1
t-
_
y
y
\
y
r
\
\
\
\
\
\
'
'
1
\
L
L
L
1
i
i
\
\
\
\
\
-^
S
\
s
-41 mm
s
-
s
s
50
jJ
Calcite (limestone)
Quartz sandstone
Dolomite
10
_I_L
10
Neutron porosity equivalence
20
30
j_I_i
20
I l_L
30
40
■ I i
10
L-Ll
20
jJ_i
30
40
jJ_i
50
jJ
50
_l
© Schlumberger
• Standard conditions
< ►
Back to Contents
73
Neutron — Wireline
APS* Accelerator Porosity Sonde
Environmental Correction — Open Hole
Schlumberger
Purpose
The Neu-10 charts pair is used to correct the APS Accelerator Porosity
Sonde apparent limestone porosity for mud weight and actual bore-
hole size. The charts are for the near-to-array and near-to-far poros-
ity measurements. The design of the APS sonde resulted in a
significant reduction in environmental correction. The answer deter-
mined with this chart is used in conjunction with the correction
from Chart Neu-11.
Description
Enter the appropriate chart pair (mud weight and actual borehole
size) for the APS near-to-array apparent limestone porosity (APLU)
or APS near-to-far apparent limestone porosity (FPLU) with the
uncorrected porosity from the APS log by drawing a straight vertical
line (shown in red) through both of the charts. At the intersection
with the mud weight value, move parallel to the closest trend line to
intersect the standard conditions line. This point represents a change
in porosity resulting from the correction for mud weight. Follow the
same procedure for the borehole size chart to determine that correc-
tion change. Because the borehole size correction has a dependency
on mud weight, even with natural muds, there are two sets of curves
on the borehole size chart — solid for light muds (8.345 lbm/gal) and
dashed for heavy muds (16 lbm/gal). Intermediate mud weights are
interpolated. The two differences are summed for the total correc-
tion to the APS log value.
This answer is used in Chart Neu-11 to complete the environ-
mental corrections for corrected APLU or FPLU porosity.
Example
Given:
Find:
Answer:
APS neutron APLU uncorrected porosity = 34 p.u.,
mud weight = 10 lbm/gal, and borehole size = 12 in.
Corrected APLU porosity.
Draw a vertical line on the APLU mud weight chart from
34 p.u. on the scale above. At the intersection with the
10-lbm/gal mud weight line, move parallel to the trend
line to intersect the standard conditions line. This point
represents a change in porosity of -0.75 p.u.
On the actual borehole size chart, move parallel to the
closest trend line from the intersection of the 34-p.u.
line and the actual borehole size (12 in.) to intersect
the 8-in. standard conditions line. This point represents
a change in porosity of -1.0 p.u.
The total correction is -0.75 + -1.0 = -1.75 p.u.,
which results in a corrected APLU porosity of
34 -1.75 = 32.25 p.u.
74
Back to Contents
Neutron — Wireline
APS* Accelerator Porosity Sonde
Environmental Correction — Open Hole
Schlumberger
Neu-10
(former Por-23a)
APS near-to-array apparent limestone porosity uncorrected, APLU (p.u.!
18
16
Mud weight 14
(Ibm/gal) 12
10
8
16
14
Actual ^2
borehole size ^
t/lud weight
(Ibm/gal)
Actual
borehole size
(in.)
14
12
10
1
1
1C
i
1 1
20
i
30
1
40
1
\
SO
1
1
/
—
,
- r
/
i
1
if
7
-lie—
= *5=
IL
if
ij
it
-+-
i
1
1
1
1
1
APS near-to-far apparent limestone porosity uncorrected, FPLU (p.u.!
2.0
1.8
1.6
1.4
1.2
1.0
400
350
300
250
200
(g/cm 3
(mm)
(g/cm 3
3====='F===^-===3F====i7===^7==== J 7==^F== = ^E==3===
|| LM 1 f#_ U U U LU. 'J ■ !
400
350
300
250
200
*Markof Schlumberger
© Schlumberger
| I I I I I I I I I | I I I I I I I I I | I I I I I I I I I | I I I I I I I I I | I I I I I I I I I |
10 20 30 40 50
• Standard conditions
< ►
Back to Contents
75
Neutron — Wireline
APS* Accelerator Porosity Sonde Without Environmental Corrections
Environmental Correction — Open Hole
Schlumberger
Neu-11
(former Por-23b)
Pressure
(psi) (MPa)
/
/
-X-\\±--\
'±nv:
10,000 69
l>snnn in?
:\ ' : \x
20,000 138
X ^A 5
5 i TlsS
Wf\
IT'S- 4V N
/
^*
jr
SiTSNatHjI
^
y
s\
/
v/N^J\wffl~T
„
**
" y
„ *
X*"\,
■•*
~^sl»
^
-' j.
S
y*
^.
*^j
r*\r
- I I I -f-p -p
^ -
<S**
**
ii --"" T~]
"Xt
r-*
.11 II.
12
11
10
9
8
7
6
5
4
3
2
1
-1
»F) 50 100 150 200 250 300 350
>C) 10 38 66 93 121 149 177
Formation temperature
50
150
250
Formation salinity
(pptorg/kg)
50 30 10
Formation porosity
(p.u.)
Apparent
porosity
correction
(p.u.)
*Markof Schlumberger
© Schlumberger
Purpose
This chart is used to complete the environmental correction for
APLU and FPLU porosities from the APS log.
Description
Enter the left-hand chart on the x-axis with the temperature of the
formation of interest. Move vertically to intersect the appropriate
formation pressure line. From that point, move horizontally right to
intersect the left edge of the formation salinity chart. Move parallel
to the trend lines to intersect the formation salinity value. From that
point move horizontally to intersect the left edge of the formation
porosity chart. Move parallel to the trend lines to intersect the
uncorrected APLU or FPLU porosity. At that intersection, move
horizontally right to read the apparent porosity correction.
Example
Given:
Find:
Answer:
APLU or FPLU porosity = 34 p.u., formation tempera-
ture = 150°F, formation pressure = 5,000 psi, and for-
mation salinity = 150,000 ppm.
Environmentally corrected APLU or FPLU porosity.
Enter the formation temperature chart at 150°F to inter-
sect the 5,000-psi curve. From that point move horizon-
tally right to intersect the left edge of the formation
salinity chart. Move parallel to the trend lines to inter-
sect the formation temperature of 150°F At this point,
again move horizontally to the left edge of the next
chart. Move parallel to the trend lines to intersect the
34-p.u. porosity line. At that point on the y-axis, the
change in porosity is +1.6 p.u.
The total correction for a corrected APLU or FPLU
from Charts Neu-10 and Neu-11 is
34 + (-0.75 + -1) + 1.6 = 33.85 p.u.
76
Back to Contents
Neutron— LWD
Schlumberger
CDN* Compensated Density Neutron, adnVISION* Azimuthal Density
Neutron, and EcoScope* Integrated LWD Tools
Mud Hydrogen Index Determination
Purpose
This chart is used to determine one of several environmental
corrections for neutron porosity values recorded with the CDN
Compensated Density Neutron, adnVISION Azimuthal Density
Neutron, and EcoScope Integrated LWD tools. The value of hydrogen
index (H m ) is used in the following porosity correction charts.
Description
To determine the H m of the drilling mud, the mud weight, tempera-
ture, and hydrostatic mud pressure at the zone of interest must
be known.
Example
Given:
Find:
Answer:
Barite mud weight = 14 lbm/gal, mud temperature = 150°F,
and hydrostatic mud pressure = 5,000 psi.
Hydrogen index of the drilling mud.
Enter the bottom chart for mud weight at 14 lbm/gal on
the y-axis. Move horizontally to intersect the barite line.
Move vertically to the bottom of the mud temperature
chart and move upward parallel to the closest trend line
to intersect the formation temperature. From the inter-
section point move vertically to the bottom of the mud
pressure chart.
Move parallel to the closest trend line to intersect the
formation pressure. Draw a line vertically to intersect
the mud hydrogen index scale and read the result.
Mud hydrogen index = 0.78.
< ►
Back to Contents
continued on next page
11
Neutron— LWD
CDN* Compensated Density Neutron, adnVISION* Azimuthal Density
Neutron, and EcoScope* Integrated LWD Tools
Mud Hydrogen Index Determination
Schlumberger
Neu-30
(former Por-1 9)
Mud hydrogen index, H m
0.70 0.75 0.80 0.85 0.90 0.95 1
1 i i i i 1 i i i i 1 i i i i 1 i i i i 1 i i i i 1 i i i i
25
t
20
Mud
pressure
(1,000 xpsi) 10
/
/
/
/
/
/
7
300
i
Mud 200
temperature
(°R
100
50
S
\
\
S
\
\
\
\
1
16
A
14
Mud
weight 12
(Ibm/gal)
10
8
v B
arit
e
Bentoni
te
0.
*Markof Schlumberger
© Schlumberger
i i i i I i i i i I i i i i I i i i i I i i i i I i i i i
70 0.75 0.80 0.85 0.90 0.95 1
78
< ►
Back to Contents
Neutron— LWD
Schlumberger
adnVISI0N475* Azimuthal Density Neutron— 4.75-in. Tool and 6-in. Borehole
Environmental Correction — Open Hole
Purpose
This is one of a series of charts used to correct adnVISION475
4.75-in. Azimuthal Density Neutron tool porosity for several environ-
mental effects by using the mud hydrogen index (H m ) determined
from Chart Neu-30 in conjunction with the parameters on the chart.
Description
This chart incorporates the parameters of borehole size, mud tem-
perature, mud hydrogen index (from Chart Neu-30), mud salinity,
and formation salinity for the correction of adnVISION475 porosity.
The following charts are used with the same interpretation
procedure as Chart Neu-31. The charts differ for tool size and
borehole size.
Example
Given:
Find:
Answer:
adnVISION475 uncorrected porosity = 34 p.u., borehole
size = 10 in., mud temperature = 150°F, hydrogen
index = 0.78, borehole salinity = 100,000 ppm, and forma-
tion salinity = 100,000 ppm.
Corrected adnVISION475 porosity.
From the adnVISION475 porosity of 34 p.u. on the top
scale, enter the borehole size chart to intersect the bore-
hole size of 10 in. From the point of intersection move
parallel to the closest trend line to intersect the stan-
dard conditions line.
From this intersection point move straight down to
enter the mud temperature chart and intersect the mud
temperature of 150°F. From the point of intersection
move parallel to the closest trend line to intersect the
standard conditions line.
Continue this pattern through the charts to read the
corrected porosity from the scale at the bottom of the
charts.
The corrected adnVISION475 porosity is 17 p.u.
< ►
Back to Contents
continued on next page
79
Neutron— LWD
Schlumberger
adnVISI0N475* Azimuthal Density Neutron— 4.75-in. Tool and 6-in. Borehole
Environmental Correction — Open Hole
Neu-31
adnVISI0N475 neutron porosity index (apparent limestone porosity) in 6-in. borehole
10 20 30 40 50
m
,"
^
«--■
**'
•
* •
Borehole
o
**
^
^
^*
*>*'
size
(in ) /
/
/
.''
rc
-•' '
^"
-"-'
^
^
/
/
/
y
.'\.
*'
*"'
*"'
6
/
/
/
/
/
,'
300
Mud
\
,
\
temperature 200
\
(°R
100
\
>
v
\
\
S \
\
\
07
•
Mud . 8 .
1
hydrogen
1
index, H m 0.9
1
1
1.0
1
200
/
/
~_l
/
Mud
/
/
/
i
f
/
salinity 100
/
1
/
. _i
1
i
/
(1,000 xppm)
/
/
1
'
J
/
/
/
/
/
1
/
'
200
•
Formation
salinity 100
\
,
,
/
/
(1,000 xppm)
/
1
J
/ _>
1
/
J
i
1
/
/
/
/
/
/
/
J
/
/
/
y
/
y
/
y
/
I I
10
*Markof Schlumberger
© Schlumberger
11 1 1 1 1
20 30 40 50
• Standard conditions
80
< ►
Back to Contents
Neutron— LWD
Schlumberger
adnVISI0N475* BIP Neutron— 4.75-in. Tool and 6-in. Borehole
Environmental Correction — Open Hole
Neu-32
adnVISI0N475 neutron porosity index (apparent limestone porosity) in 6-in. borehole
10 20 30 40 50
300
Mud 2Q0
temperature
(°F)
100
\
y
\
\
\
\
\
\
i
\
\
\
>
v
\
V
1
\
\
\
0.7
Mud 0.8
hydrogen
index, H m ab
1.0
/
1
i
/
/
/
I
1
/
I
I
/
i
*
1
1
1
/
/
1
/
j
r
i
i
/
1
Mud 200
salinity
(1,000 xppm) 10 °
/
i
i
/
1
'
/
1
l
i
1
/
1
1
1
/
/
/
1
/
1
1
/
1
/
1
1
/
/
,
1
/
1
i
/
i
I
f
1
/
/
/
t
J
i
i
1
/
f
1
i
200
Formation
salinity
(1,000 xppm)
)
)
j
1
1
/
!
1
j
J
/
I
j
/
y
/
s
/
/
/
/
/
/
/
/
'
/
f
/
/
)
<
(
*Markof Schlumberger
© Schlumberger
) 10 20 30 40 50
Purpose
This chart is used similarly to Chart Neu-31 to correct
adnVISION475 borehole-invariant porosity (BIP) measurements.
Description
Enter the top scale with the BIP neutron porosity (BNPH) to incor-
porate corrections for mud temperature, mud hydrogen index, and
mud and formation salinity.
< ►
Back to Contents
Neutron— LWD
Schlumberger
adnVISI0N475* Azimuthal Density Neutron— 4.75-in. Tool
and 8-in. Borehole
Environmental Correction — Open Hole
Neu-33
adnVISI0N475 neutron porosity index (apparent limestone porosity) in 8-in. borehole
10 20 30 40 50
I i i i i I
10
Borehole
size
(in.)
300
Mud
temperature 200
(°F)
100
0.7
8
6
r \ "\ s > \ x ^ s ^ ^
1 V \ \ Ss v ^ Ss, S ^^s ^ v ^ ^ V ^v,
\ K \ \ ^^ s s s ^v^ Vs v^ ^ n v Nv
t V V S s S ^ ^ v ^ ^ v ^ ^ v ^ ^ Nv
5 V 2k ^ ^ S ^i. ^n. ^ V b*. ^ V *.
1
|
\
Mud 08
1
\
\
\
hydrogen
1
\
1
\
\
\
index, H m 0.9
1
1
\
n
1
'
\
1.0 .
1
\
\
200
Mud
salinity 100
(1,000 xppm)
J 7 J? y y /• y
1 £ y' S' y 1 s* y*
f / / / y 4 y 4 y* y
Z Z Z z 7 Z /7 * y
j L J Z Z Z jS* y y y
200
Formation
salinity 100
(1,000 xppm)
1 T ___!_ __T__
4 i t i
1. 4 -4- i t- 4-
7 -4 / J / I j
i / z z /As'±
r
*Markof Schlumberger
© Schlumberger
n~~i
10
Purpose
This chart is used similarly to Chart Neu-31 to correct
adnVISION475 porosity.
20
30
40
I
50
• Standard conditions
82
< ►
Back to Contents
Neutron— LWD
Schlumberger
adnVISI0N475* BIP Neutron— 4.75-in. Tool and 8-in. Borehole
Environmental Correction — Open Hole
Neu-34
adnVISI0N475 neutron porosity index (apparent limestone porosity) in 8-in. borehole
10 20 30 40 50
3(10
1
\
\
\
\
\
Mud 2Q0
I
\
\
\
temperature
\
\
\
\
100
\
\
V
\
V
\
\
s
0.7
Mud 0.8
hydrogen
index, H m ab /
1.0 .
T^
/
1
1
/
/
/
/
/
1
/
/
/
/
1
/
l
'
I
/
/
/
1
/
'
/
i
/
1
/
»„ j 200 _
/
1
1
/
/
Mud
1
1
1
/
salinity
/
1
1
1
/
/
( l,uuu x ppm)
/
/
I
/
1
/
/
/
I
/
200
Formation
Mn S nn lmltV , 100
j
i
,
/
(1,000 x ppm)
1
J
J
J
/
/
I
1
/
n .
/
•
/
/
/
/
/
/
/
/
f
J
J
/
/
10 20 30 40 50
*Markof Schlumberger
© Schlumberger
Purpose
This chart is used similarly to Chart Neu-32 to correct
adnVISION475 borehole-invariant porosity (BIP) measurements.
< ►
Back to Contents
83
Neutron— LWD
adnVISION675* Azimuthal Density Neutron— 6.75-in. Tool and 8-in. Borehole
Environmental Correction — Open Hole
Schlumberger
Neu-35
(former Por-26a)
adnVISION675 neutron porosity indox (apparont limestone porosity in p.u.)
10 20 30 40 50
I I I I I I
16
14
Borehole
,in -' 10
8
300
Mud 200
temperature
(°F)
100
50
V \ S \ \ \ s s s s
\
A \ S v \ \ \ S V S \
i V ^ \ V \ \ \ s s
\ \ y \ \ \ s \ \
"1 >\>\Ks
1
: ±. _l_ l _l t. l ^l
0.7
Mud ° 8
hydrogen
index, H m 0.9
1.0
I I \ \ \ \ \ \ \
■-- 4- -I- -4- 4- -4- 4-4- XX-
\ t 4 4 \ \ V \ V
L _I_ ._[_ _i_ _1_ _\_. __L A _ V
4 4 4 \ { \ V V t
1 3 \ \ \ S S
Mud
salinity
(1,000 xppm)
250
200
100
7
t
[
,_ _ h ._._
I ___!
250
Formation
salinity
(1,000 xppm)
2.. ] T I \--l-X -X
t t ^
,00 _ L 1 ,L i I -,- 4-4
l i ijiit
o LJ_L_z_L_z_a_J_
n -1
10
n -1
20
30
H -1
40
n
50
*Markof Schlumberger
© Schlumberger
• Standard conditions
Purpose
This chart is used similarly to Chart Neu-31 to correct adnVISION675
porosity.
84
< ►
Back to Contents
Neutron— LWD
Schlumberger
adnVISION675* BIP Neutron— 6.75-in. Tool and 8-in. Borehole
Environmental Correction — Open Hole
Neu-36
adnVISI0N475 neutron porosity index (apparent limestone porosity) in 8-in. borehole
] 10 20 30 40 50
300
Mud 200
temperature
<° F >
100
1
\
\
\
\
s
I
\
\
\
\
\
\
\
'
\
\
\
\
V
\
\
S
0.7
Mud 0.8
hydrogen
index, H m °- 9
1.0
/
/
1
/
/
/
I
1
/
I
/
/
/
1
<
1
/
1
/
1
1
!
/
1
1
R/l A 200
Mud
salinity
(1,000 x ppm) 10 °
/
/
1
/
1
1
/
/
1
1
1
/
/
/
1
1
/
/
1
1
200
Formation
Mnnn linity s ™
(1,000 x ppm)
j
/
l
i
/
1
i
J
/
/
)
1
I
y
/
/
/
/
/
/
/
/
/
/
/
J
J
/
(
*Markof Schlumberger
© Schlumberger
1 1 1 1 1
1 10 20 30 40 50
Purpose
This chart is used similarly to Chart Neu-32 to correct
adnVISION675 borehole-invariant porosity (BIP) measurements.
< ►
Back to Contents
85
Neutron— LWD
adnVISION675* Azimuthal Density Neutron— 6.75-in. Tool and 10-in. Borehole
Environmental Correction — Open Hole
Schlumberger
Neu-37
(former Por-26b)
[
adnVISI0N675 neutron porosity index (apparent limestone porosity in p.u.)
10 20 30 40 50
16
14
Borehole
size 12
(in -> 10
8
300
Mud 200
temperature
(°F)
100
50
\
1
\
\
\
\
,
\
\
\
\
L
\
i
\
\
1
\
0.7
Mud °- 8
hydrogen
index, H m 0.9
1.0
\
\
\
\
\
\
A
V
\
\
i
V
\
\
\
\
I
\
\
>
\
L
\
\
*
250
200
Mud
salinity
(1,000 xppm) luu
1
j
'
/
i
i
»
/
f
/
,
i
1
j
/
/
/
/
j
/
I
1
i
i
/
/'
/
/
/'
/
250
200
Formation
salinity
(1,000 xppm) luu
,
L_
,
,
i
/
,
,
/
/
i
/
1
/
C
*Markof Schlumberger
© Schlumberger
i i i i
10 20 30 40 5
• Standard conditions
Purpose
This chart is used similarly to Chart Neu-31 to correct
adnVISION675 porosity.
86
< ►
Back to Contents
Neutron— LWD
Schlumberger
adnVISION675* BIP Neutron— 6.75-in. Tool and 10-in. Borehole
Environmental Correction — Open Hole
Neu-38
adnVISI0N675 neutron porosity index (apparent limestone porosity) in 10-in. borehole
10 20 30 40 50
snn
\
\
\
\
\
Mud 200
\
\
\
\
\
temperature
1
1
\
\
\
N
\
(°F)
100
\
\
>
\
\
\
\
\
\
\
0.7 r
Mud 0.8
hydrogen
index, H m °- 9 /
1.0 .
/
/
/
/
/
I
r
/
I
1
1
/
/
1
/
1
/
1
1
/
f
/
/
1
/
/
/
/
/
;
1
/
/
/
/
/
I
1
/
f
/
/
/
/
T
/
/
1
/
/
1
/
1
m a 200 \
Mud
salinity
I i,uuu x ppm|
200
\
1
\
\
\
v
\
Formation
\
\
\
\
\
\
\
Mnnn inity , 100
\
\
\
\
\
\
\
(1,000 xppm)
I
1
1
\
\
\
\
\
\
\
\
\
I I I I I I
10 20 30 40 50
*Markof Schlumberger
© Schlumberger
Purpose
This chart is used similarly to Chart Neu-32 to correct
adnVISION675 borehole-invariant porosity (BIP) measurements.
< ►
Back to Contents
87
Neutron— LWD
Schlumberger
adnVISION825* Azimuthal Density Neutron— 8.25-in. Tool
and 12.25-in. Borehole
Environmental Correction — Open Hole
Neu-39
°F)
Standoff = 0.25 in.
adnVISI0N825 neutron porosity index (apparent limestone porosity) in 12.25-in. borehole
1.5
1.0
Standoff
(in.) 0.5
16
Borehole u
size
12
10
300
Mud 200
temperature
(°F) 100
10
20
30
i_l_i
40
50
jj
/
/
/
/
/
/
/
7-
/
r
/
r-
/
/
/
y
y
/
y
y
/
/
/
y
/
/
t
s
/
y
y
s
y
/
f
y
/■
y
S
y
/
y
y
y
/■
y
y
y
y
y
y
y
y
y
y
I
-
y
y
y
s
y
y
w*
y
y
y
y
y
y
y
y
y
y
w»
y
y
y'
lll l lllillllill]
iliiilii
0.7
Mud 08
hydrogen
index, H m 0.9
1
20
/
/
Pressure 10
/
/
r
,000 x psi)
/
/
/
/
_
/
200
\
\
\
\
V
Mud
\
\
\
s
salinity 100
'
1
\
\
V
\
OOOxppm)
1
\
\
\
\
200
Formation
salinity 100
(1,000 xppm)
*Markof Schlumberger
© Schlumberger
i~~n
10
20
30
n~~i
40
n
50
• Standard conditions
Purpose
This chart is used similarly to Chart Neu-31 to correct
adnVISION825 porosity.
< ►
Back to Contents
Neutron— LWD
CDN* Compensated Density Neutron and adnVISION825s*
Azimuthal Density Neutron — 8-in. Tool and 12-in. Borehole
Environmental Correction — Open Hole
Schlumberger
Neu-40
(former Por-24c)
Neutron porosity index (apparent limestone porosity) in 12-in. borehole
10 20 30 40 50
i i i i i i
18
Borehole
(in.) 14
12 i
350
•
•
•
300
\
\
)
\
\
Mud
\
\
(°F)
\
\
100 _
\
\
L
50 "
4
\~
07
I
\
"
\
1
\
\
V
Mud
\
\
\
index, H m 0.9
\
\
|
\
\
\
^
1.0
L
\
\
250
200
Mud
(1,000 x ppm)
,
250
200
1
\
1
Formation
1
■
/
Mn S nn inity I "»
I
1
1
/
1
/
(1,000 x ppm)
/
/
/
/
I
/
f
/
/
/
/
/
/
/ ;
/
/
/
/
1 1 1 1 1
10 20 30 40 !
™„i.n.hi,,.h.„.. • Standard conditio
Mark of Schlumberger
© Schlumberger
1
50
ns
Purpose
This chart is used similarly to Chart Neu-31 to correct
CDN Compensated Density Neutron tool and adnVISION825s
Azimuthal Density Neutron porosity.
Back to Contents
89
Neutron— LWD
CDN* Compensated Density Neutron and adnVISION825s*
Azimuthal Density Neutron — 8-in. Tool and 14-in. Borehole
Environmental Correction — Open Hole
Schlumberger
Neu-41
(former Por-24d)
Neutron porosity index (apparent limestone porosity) in 14-in. borehole
10 20 30 40 50
is A
•
16
Borehole
(in.) 14
12 L
350
c
300
\
\
\
L
^
\
v
Mud
temperature 200
\
\
(°F)
\
,r n
100
!
50 "
r
r _>
y A
07
E
\
0.8
-\
V
•1 •
«
Mud
\
\
index, H m 09
\
\
1 n
1
\
250
G
200
i
1
\
Mud
i
1
|
/
i
I
1
salinity
(1 nnn v nnml 100 _j
I
\
/
/
I
\
>
'
1
\
I
'
1
i
1
1
1
f
/ ;
i
/
/
/
J
i
/
1
1
1
/
&
/
/
>
?5n
200
l
f
1
Formation
{
\
1
1
i
\
1
salinity
(1 000 x DDm) 100
1
1
1
1
1
1
!
_i
I
/
1
I
I
/
/
1
J
i
/
/
.1
1
1
/
1
/
/
/
>
i
/
'
/
y
/
/
/
K
10 20 30 40
"Mark of Schlumberger •Standard conditio
© Schlumberger
1
50
ns
90
< ►
Back to Contents
Neutron— LWD
CDN* Compensated Density Neutron and adnVISION825s*
Azimuthal Density Neutron — 8-in. Tool and 16-in. Borehole
Environmental Correction — Open Hole
Schlumberger
Neu-42
(former Por-24e)
c
Nautron porosity index (apparent limestone porosity) in 16-in. borehole
10 20 30 40 \
10
J
18
16
Borehole
size
(in.) 14
12
350
•
300
Mud
temperature 200
(°F)
100
50
"\
\
\
\
L
\
_.
-.
J
■ -
-- J
0.7
0.8
Mud
hydrogen
index, H m 09
1
•
•
250
200
Mud
salinity
(1,000 xppm) 10°
|
I
1
i
1
l
1
/
i
J
/
1
1
1
1
f
/
/
I
1
j
1
/
r
L
/
/
1
/
/
/
/
/
250
200
Formation
salinity
(1,000 xppm) 10°
i
j
'
1
1
1
1
i_
j
1
j
j
f
1
1
J
1
J
/
/
1
1
1
/
1
/
1
/
/
/
/
/
C
*Markof Schlumberger
© Schlumberger
i i i i
10 20 30 40 !
• Standard conditio
1
50
ns
< ►
Back to Contents
Neutron— LWD
Schlumberger
EcoScope* Integrated LWD Neutron Porosity — 6.75-in. Tool
Environmental Correction — Open Hole
Purpose
Charts Neu-43 through Neu-46 show the environmental corrections
that are applied to EcoScope 6.75-in. Integrated LWD Tool neutron
porosity measurements. These charts can be used to estimate the
correction that is normally already applied to the field logs.
Description
The charts incorporate the parameters of borehole size, mud tem-
perature, mud hydrogen index (from Chart Neu-30), mud salinity,
and formation salinity for the correction of EcoScope 6.75-in.
neutron porosity.
Select the appropriate chart based on both the hole size and
the measurement type: thermal neutron porosity (TNPH) or best
thermal neutron porosity (BPHI).
Enter the charts with the uncorrected neutron porosity data.
Charts Neu-43 and Neu-44 are for use with BPHIJJNC, and Charts
Neu-45 and Neu-46 are for use with TNPH_UNC. Because the bore-
hole size correction is applied to the field logs, including the _UNC
channels, do not include the borehole size correction, which is in the
charts for illustrative purposes only.
A correction for eccentricity effects is normally also applied to
the field BPHI measurement. Because this correction is not included
in these charts, there may be a small difference between the correc-
tion estimated from the charts and that actually applied to the field
data, depending on the tool position in the borehole.
The charts are used with a similar procedure to that described
for Chart Neu-31.
92
Back to Contents
Neutron— LWD
Schlumberger
EcoScope* Integrated LWD BPHI Porosity — 6.75-in. Tool and 8.5-in. Borehole
Environmental Correction — Open Hole
Neu-43
EcoScope uncorrected BPHI porosity (apparent limestone porosity in p.u.) in 8.5-in. borehole
10 20 30 40 50
i i i i i i
14
4
/
-1 •
13 .
1
/
'
/
t
i
12
/
Borehole
/
_,
1
/
/
(m.) io
/
/
1
9 .
J
/
'
8.'
t
n
,
260 .
\
\
\
210 .
\
\
loci 160 .
1
( H
'
110 .
.
]
\
60
1
70
1
0.75 _
1
1
0-80 -
L
1
Mud
1
index, H m .90 "
1
0.95
:
.
1.00
250
.
7
200
7
1
,
7
I
j
Mud 150
t
I
7
1
r
1
7
1
r
7
_7
(1,000 xppm)
f
_f
50 .
_
±
r
_f
1
_
__
250
200
Formation 150
salinity 1f)n
(1,000 xppm)
50
V
L
\
Y
1
1
\
\
>
1
\
\
1
I
\
,
)
\
\
\
\
\
\
\
I
i
\
\
\
i
\
\
\
\
\
1
\
\
1
\
\
\
\
\
\
1 1 1 1 1
10 20 30 40 !
*Markof Schlumberger
©Schlumberger • Standard conditi
1
so
ns
Purpose
This chart is used similarly to Chart Neu-31 to estimate the correc-
tion applied to EcoScope 6.75-in. Integrated LWD Tool best thermal
neutron porosity (BPHI) measurements.
Use this chart only with EcoScope BPHI neutron porosity; use
Chart Neu-45 with EcoScope thermal neutron porosity (TNPH)
measurements.
Back to Contents
93
Neutron— LWD
Schlumberger
EcoScope* Integrated LWD BPHI Porosity — 6.75-in. Tool and 9.5-in. Borehole
Environmental Correction — Open Hole
Neu-44
EcoScope uncorrected BPHI porosity (apparent limestone porosity in p.u.) in 9.5-in. borehole
10 20 30 40 50
i i i i i i
14
1
•
13 .
/
12
f
r
Borehole
,
j
/
/
/
(m.) io
/
/
7
9 .
/
/
/
t
R /
/
'
T
\
" - 1
i
260 _
1
\
\
\
\
210
\
\
,
^
\
loci 160 _
h
\
In
1
\
110 _
1
I
\
\
60
]
70
1
0.75 _
r
1
0-80 -
1
1
Mud
1
1
1
1
j
T
"
"
1
index, H m .90 "
3
1
j
r
r
1
0.95
n
I
I
J
1.00
PRO
I
:t
1
•
200
T
j
|
1
i
Mud 150
1
i
T
4
Mnnn I 100
r
t
(1,000 xppm)
r
i
50 .
1
±
/
.
„_
1
j
250
i
\
\
200 .
\
}
\
\
1
\
\
\
Formation 150 .
_
\
i
i
\
1
I
\
\
\
salinity m
L
\
\
\
\
(1,000 xppm)
t
L
\
\
\
\
50
H
\
\
\
\
\
\
\
i
'
i
\
_L
i
v_
\
\
1 1 1 1 1
10 20 30 40 !
*Markof Schlumberger
©Schlumberger • Standard conditi
1
SO
ns
Purpose
This chart is used similarly to Chart Neu-31 to estimate the correc-
tion applied to EcoScope 6.75-in. Integrated LWD Tool best thermal
neutron porosity (BPHI) measurements.
Use this chart only with EcoScope BPHI neutron porosity; use
Chart Neu-46 with EcoScope thermal neutron porosity (TNPH)
measurements.
94
Back to Contents
Neutron— LWD
Schlumberger
EcoScope* Integrated LWD TNPH Porosity — 6.75-in. Tool and 8.5-in. Borehole
Environmental Correction — Open Hole
Neu-45
EcoScope uncorrected TNPH porosity (apparent limestone porosity in p.u.) in 8.5-in. borehole
10 20 30 40 50
i i i i i
14
13
12
Borehole
size 11
(m.) 10
9
8
r
■i •
-I
\
/
\
1
1
/
1
1
j
1
/
1
/
1
1
/
7
1
/
I
/
/
L
260
210
Temperature
{op) 160
110
60
r
\
.
t
\
\
I
\
I
\
\
1
\
\
1
\
,
i
\
0.70
0.75
Mud °- 8 °
hydrogen 0.85
index, H m n.grj
0.95
1.00
1
T
v_
1
i_
L
r
r
1
T
F
I
T
x_
1
T
T
1
1
1
.
1
.
250
200
Mud 150
nnnn" mty i 100
(1,000 xppm)
50
T
j •
T
f
f
r
f
f
r
r
_
250
200
Formation 150
Mnnn initV , 100
(1,000 xppm)
50
\
— ,
1
\
1
1
\
\
\
: l
\
1
\
i
.
\
\
1
i
\
,
,
r
\
]
]
!
i
\
1
\
(
*Markof Schlumberger
© Schlumberger
... .
) 10 20 30 40 50
• Standard conditions
Purpose
This chart is used similarly to Chart Neu-31 to estimate the correc-
tion applied to EcoScope 6.75-in. Integrated LWD Tool thermal neu-
tron porosity (TNPH) measurements.
Use this chart only with EcoScope TNPH measurements. Use
Chart Neu-43 with EcoScope best thermal neutron porosity (BPHI)
measurements.
Back to Contents
95
Neutron— LWD
Schlumberger
EcoScope* Integrated LWD TNPH Porosity — 6.75-in. Tool and 9.5-in. Borehole
Environmental Correction — Open Hole
Neu-46
EcoScope uncorrected TNPH porosity (apparent limestone porosity in p.u.) in 9.5-in. borehole
10 20 30 40 50
i i i i i i
14
i
n
-l •
13 .
f
I
12
/
Borehole
(m.) io
\
f
9 .
.
R /
,
1
260 _
\
\
\
\
210 _
V
\
\
loci 160 _
L
\
In
1
y
110 _
60
t
70
0.75 _
0-80 -
Mud
index, H m .90 "
0.95
1.00
250
i
J •
200
4
t
7
j
Mud 150
T
j
.
.
_,
T
T
Mnnn I 100
f
T
J
(1,000 xppm)
f
J
r
50
T
r
J
I
1
■
X
250
J
\
200
\
i
\
\
1
\
i
\
Formation 150 .
\
\
\
r
1
I
\
I
salinity 100 ;
L
\
\
(1,000 xppm)
„
;
\
\
50
I
\
\
\
I
1
\
\
\
3
\
\
>
1 1 1 1 1 1
10 20 30 40 50
*Markof Schlumberger
© Schlumberger • Standard conditions
Purpose
This chart is used similarly to Chart Neu-31 to estimate the correc-
tion applied to EcoScope 6.75-in. Integrated LWD Tool thermal neu-
tron porosity (TNPH) measurements.
Use this chart only with EcoScope TNPH neutron porosity; use
Chart Neu-44 with EcoScope best thermal neutron porosity (BPHI)
measurements.
96
Back to Contents
Neutron— LWD
EcoScope* Integrated LWD — 6.75-in. Tool
Formation Sigma Environmental Correction — Open Hole
Schlumberger
Purpose
This chart is used to environmentally correct the raw sigma (RFSA)
measurement for porosity, borehole size, and mud salinity. The fully
corrected sigma (SIFA) measurement is normally presented on the
logs.
Description
Chart Neu-47 includes (from top to bottom) the moments sigma
transform, diffusion correction based on porosity, and borehole
correction.
Example
Given: Raw sigma (24 c.u.), porosity (30 p.u.), borehole size
(10 in.), and mud salinity (200,000 ppm).
Find: Corrected sigma (SIFA).
Answer: Enter the chart from the scale at the top with the raw
sigma value of 24 c.u.
Moments Sigma Transform
Move parallel to the closest trend line to intersect the x-axis of the
moments sigma transform chart. The difference between the x-axis
value and the raw sigma value is the moments sigma transform
correction (19.8 - 24 = -4.2 c.u.).
Diffusion Correction
Move down vertically from the scale at the top to intersect the
30-p.u. line on the porosity chart. At the intersection point, move
parallel to the closest trend line to intersect the x-axis of the
porosity chart.
The difference between the x-axis value and the raw sigma value
is the diffusion correction (25.3 - 24 = +1.3 c.u.).
Borehole Correction
Move down vertically from the scale at the top to intersect the 10-in.
borehole size line. At the intersection point, move parallel to the
closest trend line corresponding to the mud salinity to intersect
the x-axis of the borehole correction chart.
The difference between the x-axis value and the raw sigma value
is the borehole correction (22.8 - 24 = -1.2 c.u.).
Net Correction
The net correction to apply to the raw sigma value is the sum the
three corrections (-4.2 + 1.3 + -1.2 = -4.1 c.u.). The environmentally
corrected sigma is the sum of the net correction and the raw sigma
value (24 + -4.1 = 19.9 c.u.).
EcoScope Sigma Correction Example
Correction
Raw sigma
24 c.u.
Porosity
30 p.u.
Borehole size
10 in.
Mud salinity
200,000 ppm
Moments sigma transform
-4.2 c.u.
Porosity correction
+1.3 c.u.
Borehole correction
-1.2 c.u.
Net correction
-4.1 c.u.
Environmentally corrected sigma
19.9 c.u.
< ►
Back to Contents
continued on next page
97
Neutron— LWD
Schlumberger
EcoScope* Integrated LWD — 6.75-in. Tool
Formation Sigma Environmental Correction — Open Hole
Neu-47
Momonts
sigma
transform
Porosity
(p.u.)
Boreholo
sizo (in.)
*Markof Schlumberger
© Schlumberger
1
)
10 20
1 , , , , 1 ,
Raw sigma (c.u.)
30 40 50 60
/
/
A
/
/
X
y
^
s
^
S
so
40
30
20
10
1
I
1
I
1
1
I
I
1
1
I
I
]_
t
1
1^
t
I
\
\
t
I
i
\
\
i
\
1
\
\
I
i
\
J
\
^r
\
j
11
10
9
R
1
!
/
\
\
N,
\
\
I
/
\
\\
\
\
\
/
1
'
\\
r
V
\
\
/
1
I
\l
\
\
\
\
/
1
\\
\
V
/
i
1
V
t /
\
\
/
/
1
j
\
\
\\
\
/
/
1
/
\
\
V
A
/
/
1/
>
\\
/
Mud salinity
ppm
50,000 ppm
100,000 ppm
150,000 ppm
200,000 ppm
/
V
V
i
\tt
1
\
i
1
1
i'
1
)
| i i i i | i
10 20
30 40 50 60
• Standard conditions
98
< ►
Back to Contents
Nuclear Magnetic Resonance — Wireline
CMR*Tool
Hydrocarbon Effect on NMR/Density Porosity Ratio
Schlumberger
CMR-1
Pb
(g/cm 3
1.4
1.6
1.8
2.0
2.2
2.4
2.6
1.0
0.8
0.6
0.4
0.2
Ph = 0.8
^06
^0.5
v^a4
\02
\0.1 ^
0.2
Fresh Mud and Dry Gas at 700 psi
p ma = 2.65,p f =1,l,= 1,p gas = 0.25,
PT = 4, T, gas = 4, l H = 0.5
0.4 0.6
1-S V „
0%
20%
1 1
Porosity = 50 p. u.
40%
dn
60%
).U. —
" 80%
G
as /
30 p. u
100%
_20[
^xo~
-10 p
^Wa
ter
Pb
(g/cm 3
0.8 1.0
Fresh Mud and Dry Gas at 700 psi
p ma = 2.71, Pf = 1,l f =1, Pgas = 0.25,
PT = 4,T ig as = 4,l gas = 0.5
0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40 0.45 0.50
0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40 0.45 0.50
*Markof Schlumberger
© Schlumberger
Purpose
This chart is used to determine the saturation of the flushed zone
(Sxo) and hydrocarbon density (ph) by using density (p) and CMR
Combinable Magnetic Resonance data.
Description
The top chart has three components: ratio of total CMR porosity
to density porosity (<])tcMRA]>D) on the y-axis, (1 - Sxo) values on the
x-axis, and ph defined by the radiating lines from the value of unity
on the y-axis. Enter the chart with the values for (1 - Sxo) and the
<|)tcMR/<j)D ratio. The intersection point indicates the hydrocarbon
density value. The bottom charts are used to determine the Sxo value
in sandstone (left) and limestone (right).
Example
Given: CMR porosity = 25 p.u., §v = 30 p.u., and S xo = 80%.
Find: Hydrocarbon density of the fluid in the formation.
Answer: <|>tcMR/<|>D ratio = 25/30 = 0.83.
1 - Sxo = 1 - 0.8 = 0.20 or 20%.
For these values, ph = 0.40.
Back to Contents
99
This page intentionally left blank.
< ►
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Resistivity Laterolog — Wireline
ARI* Azimuthal Resistivity Imager
Environmental Correction — Open Hole
Schlumberger
RLI-1
(former Rcor-14)
3 5 /a-in. Tool Centered, Active Mode, Thick Beds
1.5
6__
R,/R a 1.0
/<
<Z
/
?
"
-- J0__
A
/
&
**
\
- \L
ole diameter (in
r
/
0.5
10
100
FL/FL
*Markof Schlumberger
© Schlumberger
1,000
10,000
Purpose
This chart is used to environmentally correct the ARI Azimuthal
Resistivity Imager high-resolution resistivity (LLhr) curve for the
effect of borehole size.
Description
For a known value of resistivity of the borehole mud (R m ) at the zone
of interest, a correction for the recorded log azimuthal resistivity (R a )
is determined by using this chart. The resistivity measured by the
ARI tool is equal to or higher than the corrected resistivity (Rt) for
borehole sizes of 8 to 12 in. However, the measured ARI resistivity
is lower than Rt in 6-in. boreholes and for values of R a /R m between
6 and 600.
Example
Given:
Find:
Answer:
ARI LLhr resistivity (R a ) = 20 ohm-m, mud resistivity
(R m ) = 0.02 ohm-m, and borehole size at the zone of
interest = 10 in.
True resistivity (Rt).
Enter the chart at the x-axis with the ratio R a /R m =
20/0.02 = 1,000.
Move vertically upward to intersect the 10-in. line. Move
horizontally left to read the Rt/R a value on the y-axis
of 0.86.
Multiply the ratio by R a to obtain the corrected LLhr
resistivity:
Rt = 0.86 x 20 = 17.2 ohm-m.
Back to Contents
101
Resistivity Laterolog — Wireline
High-Resolution Azimuthal Laterolog Sonde (HALS)
HLLD Borehole Correction — Open Hole
Schlumberger
RLI-2
R./HLLD
R t /HLLD
1.2
1.1
1.0
0.9
0.8
0.7
0.6
10-
1.5
10°
HLLD Tool Centered (R m =0.1ohm-m)
10°
10'
10 2
HLLD/R m
10 3
5 ir
.
4
* *
:■----
t>.
■•^:
3 in.
3 in.
10 in.
12 in.
14 in.
16 in.
*
y
^7*~
<>
•^8
^
2^fc
'in
in
10"
10=
Borohole Effect, HLLD Tool Centered (R m = 0.1 ohm-m)
c
b
1 3
f in.
.8 in.
10 in.
12 in.
1 1
-
14 in.
16 in.
•"S
■::=-=n
-
18 in.
9H in
> '
■«.
nq
^<^
0.7
^^_
='i^
0.5
10'
10 2 10 3 10 4
HLLD/R m
10=
© Schlumberger
Purpose
This chart is used to correct the HALS laterolog deep resistivity
(HLLD) for borehole and drilling mud effects.
Description
Enter the chart on the x-axis with the value of HLLD divided by
the mud resistivity (R m ) at formation temperature. Move upward
to intersect the curve representing the borehole diameter (dh), and
then move horizontally left to read the value of the ratio Rt/HLLD on
the y-axis. Multiply this value by the HLLD value to obtain Rt. Charts
RL1-3 through RL1-14 are similar to Chart RL1-2 for different resistivity
measurements and values of tool standoff.
Example
Given:
Find:
Answer:
HLLD = 100 ohm-m, R m = 0.02 ohm-m at formation
temperature, and borehole size = 10 in.
Rt.
Ratio of HLLD/R m = 100/0.02 = 5,000.
Rt = 0.80 x 100 = 80 ohm-m.
102
Back to Contents
Resistivity Laterolog — Wireline
High-Resolution Azimuthal Laterolog Sonde (HALS)
HLLS Borehole Correction — Open Hole
Schlumberger
RLI-3
HLLS Tool Centered (FL = 0.1 ohm-m)
3.0
2.5
2.0
R./HLLS 1-5
1.0
0.5
10-
5 in
1
1
1
1
8 in
. 10 i
12i
14i
16i
n.
i
1
1
1
1
n.
n.
n.
/
/
1
1
1
1
1
1
1
1
S5.
s_=
..'■----
-"
•
#•
_
/
s
s
f
ii"**
-..:::
10°
10'
10 2
HLLS/R,
10 3
10"
10=
) Schlumberger
3.0
Borehole Effect, HLLS Tool Centered (R m = 0.1 ohm-m)
2.5
c
6
8
h
in.
1
1
1
1
J
I
1
1
L
10 in.
12 in.
1/1 \n
1
1
1
1
/
1
i'
1
1
1
1
1
2.0
R./HLLS 1.5
16 in.
18 in.
?n in
1
1
1
/
1
1
/
/
1
/
/
■ -
-
~'.:
*
*
--
_
--
/
/
1.0
<*
«s
s; ^
b'S:%i
0.5
10°
10'
10 2 10 3
HLLS/R m
Purpose
This chart is used similarly to Chart RL1-2 to correct HALS laterolog
shallow resistivity (HLLS) for borehole and drilling mud effects.
10 4
10=
< ►
Back to Contents
103
Resistivity Laterolog — Wireline
High-Resolution Azimuthal Laterolog Sonde (HALS)
HRLD Borehole Correction — Open Hole
Schlumberger
RLI-4
HRLD Tool Centered (R m = 0.1 ohm-m)
) Schlumberger
R t /HRLD
R t /HRLD
1.1
1.0
0.9
0.8
0.7
0.6
0.5
0.4
10-
1.4
10°
j in.
bin.
8 in.
10 ir
1 2 ir
14 ir
16 ir
-/-'
- >.
X*-*
- ~^.
/
'-
'/'
•s
V
N
>
"V
V
.
r 'it
i /
r
Jr
s
X
■«.
10°
10 1
10 2
HRLD/R m
10 3
10"
10 5
Borehole Effect, HRLD Tool Centered (R m = 0.1 ohm-m)
c
h
1 ?
8 in.
10 in.
_. 12 in.
1 n
--
_. 14 in.
. 16 in
^r
„.
w i,T
" '" -TT 1
--
_. 18 in.
20 in.
-■ ,_ ^
f—
-
---..
^
--.
..."-
OR
w *'
-
-
"■* „,
"■■».,
^
--.
• ..
Ofi
/
■ „ > ■*■
-.
* .„
"--
*■
-
■-..
_
n.4
10'
10 2 10 3
HRLD/R m
10 4
10=
Purpose
This chart is used to similarly to Chart RL1-2 to correct the HALS
high-resolution deep resistivity (HRLD) for borehole and drilling
mud effects.
104
< ►
Back to Contents
Resistivity Laterolog — Wireline
High-Resolution Azimuthal Laterolog Sonde (HALS)
HRLS Borehole Correction — Open Hole
Schlumberger
RLI-5
HRLS Tool ContorGd (R m = 0.1 ohm-m)
R./HRLS
3.0
2.5
2.0
1.5
1.0
0.5
10-'
10°
10'
10 2
HRLS/R,
5 i r
i ir
.
1
1
J .
3 in.
Oin.
in
1
1
1
,1
1
14in.
16 in.
1
1
1
1
1
1
1
1
• •
1
1
_^*^,
:"■■-'
10 3
10 4
10 5
© Schlumberger
3.0
R t /HRLS
Borehole Effect, HRLS Tool Centered (R m = 0.1 ohm-m)
?R
d,
6
8
n.
n
\
1
1
1
?n
10 in.
12 in.
1 A in
1
1
1
1
1
1
1
1 5
IE
1£
2C
in.
in.
in.
1
1
1
1
1
1
1
1
1
1
1
1
-
^
/
/
>
,.
/
/
*
p „ ■
1.0
05
4
^
-
e
!:S=
10"
10'
10 2 10 3
HRLS/R m
Purpose
This chart is used to similarly to Chart RL1-2 to correct the HALS
high-resolution shallow resistivity (HRLS) for borehole and drilling
mud effects.
10 4
10=
< ►
Back to Contents
105
Resistivity Laterolog — Wireline
High-Resolution Azimuthal Laterolog Sonde (HALS)
HLLD Borehole Correction — Eccentered in Open Hole
Schlumberger
RLI-6
HLLD Tool Ecconterod at Standoff = 0.5 in. (R m = 0.1 ohm-m)
) Schlumberger
1.2
1.1
1.0
R./HLLD 09
0.8
0.7
0.6
10-'
R t /HLLD
1.2
1.1
1.0
0.9
0.8
0.7
0.6
10-'
d h
5 in.
6 in.
8 in
10 in.
*
_j--s
- \L III.
14 in.
16 in.
%
/
/j
1
^
H
» '.V
ft
1
'V
10"
10'
10 2
HLLD/R m
10 3
10 4
10=
HLLD Tool Eccentored at Standoff = 1.5 in. (R m =0.1 ohm-m)
d h
Bin.
in in
*■-"
-■ — -»
12 in.
14 in.
16 in.
4
/
*
'S
N
^
//
/ K
1
*
^
S"
"
4 *^Si
10"
10'
10 2
HLLD/R m
10 3
10 4
10 5
Purpose
This chart is used to similarly to Chart RL1-2 to correct the HALS
laterolog deep resistivity (HLLD) for borehole and drilling mud effects
at 0.5- and 1.5-in. standoffs.
106
< ►
Back to Contents
Resistivity Laterolog — Wireline
High-Resolution Azimuthal Laterolog Sonde (HALS)
HLLS Borehole Correction — Eccentered in Open Hole
Schlumberger
RLI-7
3.0
HLLS Tool Eccontorod at Standoff = 0.5 in. (R m = 0.1 ohm-m)
2.5
2.0
R t /HLLS 1 - 5
1.0
0.5
d h
5 in.
6 in.
8 in.
10 in
12 in
14 in
16 in
1
1
i
i
i
1
1
1
r
i
i
i
1
1
I 1
/
/
/
i
i
/
•
•
s
•
<•*
•
-•■
? ?l
,
10-' 10° 10 1 10 2 10 3
HLLS/R m
HLLS Tool Eccontored at Standoff = 1 .5 in. (R m = 0.1 ol
3.0
10"
lm-m)
10=
2.5
2.0
R./HLLS 1.5
1.0
0.5
d h
8 in.
10 ir
1 2 ir
14 ir
16 ir
i
i
/
i
i
i
:
i
/
/
;
/
/
1
/
f
/
i
i
/
/
„. '£
:.'--
s
/
.»
-
/
*•
*
/
V
,-**■
1
© Schlumberger
0-'
10°
10 1
H
10 2
LLS/R m
10 3
10"
10=
Purpose
This chart is used to similarly to Chart RL1-2 to correct the HALS
laterolog shallow resistivity (HLLS) for borehole and drilling
mud effects at 0.5- and 1.5-in. standoffs.
< ►
Back to Contents
107
Resistivity Laterolog — Wireline
Schlumberger
High-Resolution Azimuthal Laterolog Sonde (HALS)
HRLD Borehole Correction — Eccentered in Open Hole
RLI-8
HRLD Tool Eccontered at Standoff = 0.5 in. (R m = 0.1 ohm-m)
) Schlumberger
R./HRLD
R./HRLD
1.1
1.0
0.9
0.8
0.7
0.6
0.5
0.4
d
5
h
in.
bin.
8 in.
10 in
12 in
14 in
16 in
/ / y f
f f /
'-
«•
" '■ -m ^
■
//'
■* - *
■*»
r>
*V
-
X
■V
"*
^ ..
• '
"
10-
10°
10'
10 2
HRLD/R m
10 3
10 4
10=
HRLD Tool Eccentored at Standoff =1.5 in. (R m =0.1 ohm-m)
1.1
1.0
0.9
0.8
0.7
0.6
0.5
0.4
c
in
10 in
12 in
14 in
16 in
.
i s
f /
-
-
--
"*■*
-.
"S
1
t '
1°
'■ *»
N.
N.
'/
V
X
X
' ■
X
-..
I
'-■-.
1
10-'
10"
10 1
10 2
HRLD/R m
10 3
10"
10 5
Purpose
This chart is used to similarly to Chart RL1-2 to correct the HALS
high-resolution deep resistivity (HRLD) for borehole and drilling
mud effects at 0.5- and 1.5-in. standoffs.
108
< ►
Back to Contents
Resistivity Laterolog — Wireline
High-Resolution Azimuthal Laterolog Sonde (HALS)
HRLS Borehole Correction — Eccentered in Open Hole
Schlumberger
RLI-9
HRLS Tool Eccentered Standoff = 0.5 in. (R_ = 0.1 ohm-m)
3.0
2.5
2.0
R./HRLS 1 - 5
1.0
0.5
10-'
10°
10 1
d h
5 ir
.
. 8 in.
10 in.
iz in.
14 in.
16 in.
/
/
;
i
*
i
i
i
i
/
/
i
i
i
V
k 1
>.; S="
-.
10 2
HRLS/R m
10 3
10 4
10=
) Schlumberger
HRLS Tool Eccentered Standoff = 1.5 in. (R m =0.1 ohm-m)
3.0
R./HRLS
10-'
10"
R in
1
1
25
m i
?n
12i
14 i
16 i
1.
1.
1
1
1
1
1
I
I
I
I
1
1
1
1
1
1
1 5
i n
y
I
/
t'
f
1
1
/
1
05
10'
10 2
HRLS/R m
Purpose
This chart is used to similarly to Chart RL1-2 to correct the HALS
high-resolution shallow resistivity (HRLS) for borehole and drilling
mud effects at 0.5- and 1.5-in. standoffs.
10 3
10 4
10 5
< ►
Back to Contents
109
Resistivity Laterolog — Wireline
HRLA* High-Resolution Laterolog Array
Borehole Correction — Open Hole
Schlumberger
RLI-10
3.0
2.5
2.0
R t /RLA1 1-5
1.0
0.5
Tool Centered
10-'
3.0
2.5
2.0
R./RLA1 1.5
1.0
0.5
10-
3.0
2.5
2.0
R t /RLA1 1.5
1.0
0.5
10-'
*Markof Schlumberger
© Schlumberger
1
1
1
1
1
1
I
;
/
f
1
1
1
1
1
I
( 1
1
'
1
/
r
/
1
/
/
/
k'>
£
*
s
*::'
ii
' '
™
y
/
10°
10'
10 2 10 3
RLA1/R m
Standoff = 0.5 in.
W
10 5
10°
10'
10 2 10 3
RLA1/R m
Standoff = 1.5 in.
10 4
10 5
10 6
i r /
i
i
i
l_
f ' /
i
i
i
\
Jl]
II 1
i /
\' \j >
if i
1
!
L *'
<
"m
H '
- —
— —
-■■■—-
10 6
I
j
—1
I
I
i
n.
/ '
i /
r /
I I
I
I
I
6 in.
. 8 in.
ii
ii
' I '
/ 1
/ I
1 I
I
I
bin.
10 in.
12 in.
14 in.
16 in.
18 in.
__ 20 in.
22 in.
A
/i
*
*
--
v
'S
10°
10'
10 2
10 3
10 4
10=
10 6
RLA1/R m
Purpose effects. RLA1 is the apparent resistivity from computed focusing
This chart is used to similarly to Chart RL1-2 to correct HRLA High- mode 1.
Resolution Laterolog Array resistivity for borehole and drilling mud
110
< ► Back to Contents
Resistivity Laterolog — Wireline
HRLA* High-Resolution Laterolog Array
Borehole Correction — Open Hole
Schlumberger
RLI-11
3.0
2.5
2.0
R,/RLA2 1.5
1.0
0.5
Tool Centered
/,
1
1
1
i
i
i
/ /
1
1
i
i
i
/
1
> /
/
/
1
1
1
i
1
i
/s
s
s
^
s
'
_
/
■:llu -
V
1 ' '-A
'/
10-'
10°
10'
3.0
2.5
2.0
R t /RLA2 1 - 5
1.0
0.5
10 2 10 3
RLA2/R m
Standoff = 0.5 in.
10"
10 5
10 6
10-'
1 ' /
1 ' /
1 ' /
1
I
1
1
/
1
/ ' /
/ /
1
1
1
1
1
1
,' 1
/ / /
1
1
/
*' s
'
t
•=
^•**'/>\
: : — :
z ==:
:i:= ^
: := =
10°
10'
3.0
2.5
2.0
R t /RLA2 1-5
1.0
0.5
10 2 10 3
RLA2/R m
Standoff =1.5 in.
10 4
10 5
10 6
1 1
/ J
1 /
1
1
1
1
1
1
1
1 1
1
1
1
1
1
1
1 /
/ /
/
/
1
1
1
1
<*>
•
•
/
.-
-
-
'
fj.r
10 '
10°
10'
10 2
10 3
10 4
10=
10 6
*Markof Schlumberger
© Schlumberger
5 in.
6 in.
8 in.
9 in.
10 in.
12 in.
14 in.
16 in.
18 in.
20 in.
22 in.
RLA2/R m
Purpose effects. RLA2 is the apparent resistivity from computed focusing
This chart is used to similarly to Chart RL1-2 to correct HRLA High- mode 2.
Resolution Laterolog Array resistivity for borehole and drilling mud
< ►
Back to Contents
in
Resistivity Laterolog — Wireline
HRLA* High-Resolution Laterolog Array
Borehole Correction — Open Hole
Schlumberger
RLI-12
R t /RLA3
3.0
2.5
2.0
1.5
1.0
0.5
Tool Centered
10-
10°
R t /RLA3
3.0
2.5
2.0
1.5
1.0
0.5
10-
10°
R t /RLA3
3.0
2.5
2.0
1.5
1.0
0.5
10-'
1
7
I
1
i j
1
i 1
r
1
1
/
J
f /
/
1
1
t
1
.,;<. ■*
-•"T^ - — "
s
•
*
; v£
JJf
r:::
z ==z: .=
=:.:= =
=:
=:
__ —
r:::
-■—-■-
-■-■—-
::::::
' ' f t
10'
10 2 10 3
RLA3/R m
Standoff = 0.5 in.
10 4
10 5
10 6
1
1
/
;
/
;
/
/
/
/
:
/
1
1
i
1
1
1 i
I 1
l
/
/
1
1
<*
/ -
/ .
-'
^
-
/
/
•4*
«r
;;;
; .
10'
10 2 10 3
RLA3/R m
Standoff = 1.5 in.
10 4
10=
10 6
1
1
1
1
1
1
1
1
1
1
1
1
1
/
/
/
/ /
* /
1
/
/
1
;
4
/
1
J
1
f<
»
*
zz
_
-
/
/
■ '
■.■•
Jj
>*
■'■■'
10"
10'
*Markof Schlumberger
© Schlumberger
10 2 10 3
RLA3/R m
10 4
10=
10 6
d h
—
—
5 in.
—
—
6 in.
8 in.
9 in.
10 in.
--
--
12 in.
14in.
--
--
16 in.
18 in.
—
—
20 in.
22 in.
Purpose effects. RLA3 is the apparent resistivity from computed focusing
This chart is used to similarly to Chart RL1-2 to correct HRLA High- mode 3.
Resolution Laterolog Array resistivity for borehole and drilling mud
112
< ► Back to Contents
Resistivity Laterolog — Wireline
HRLA* High-Resolution Laterolog Array
Borehole Correction — Open Hole
Schlumberger
RLI-13
R t /RLA4
3.0
2.5
2.0
1.5
1.0
0.5
Tool Centered
10-'
i
i
i
1
i
)
i
i
/
/
i
i
1
/
i
i
i
_ — -
.'
•
*•
'
.. — —
—
—
-__
^
3
-z
~
V
10°
10'
R t /RLA4
3.0
2.5
2.0
1.5
1.0
0.5
10 2 10 3
RLA4/R m
Standoff = 0.5 in.
10 4
10=
10-'
10°
10 1
R t /RLA4
3.0
2.5
2.0
1.5
1.0
0.5
10 2 10 3
RLA4/R m
Standoff =1.5 in.
10 4
10=
10-'
10°
10 1
10 2
10 3
10 4
10 5
*Markof Schlumberger
© Schlumberger
RLA4/R,
10 6
/
/
i
1
1
1
/
1
/
/
/
1
1
1
1
1
1
1
;*?*■
•
'-
s
/
s
*
1
•—
■
■ ,- -,
"7
_
■ ■■
-- -
-
~
ai£24
imiii
■ ■-■ ■■ ■ i-
10 6
1 '
1 '
/
1
/
r
/
1
f
1
1
/
/
/
r
' .<
1
/
/
/
T "
\
1
1
<*-■;[
■■'}:J^-
^
**
. .-'
/
•
•
•^0
w*
ft^t
: : "
uini
TWMTiT
10 6
5 in.
6 in.
8 in.
9 in.
10 in.
12 in.
14 in.
16 in.
18 in.
20 in.
22 in.
Purpose
effects. RLA4 is the apparent resistivity from computed focusing
This chart is used to similarly to Chart RL1-2 to correct HRLA High- mode 4.
Resolution Laterolog Array resistivity for borehole and drilling mud
< ►
Back to Contents
113
Resistivity Laterolog — Wireline
Schlumberger
HRLA* High-Resolution Laterolog Array
Borehole Correction — Open Hole
RLI-14
R t /RLA5
3.0
2.5
2.0
1.5
1.0
0.5
Tool Centered
10-'
_ -
•
-
'<,
^
=='==
«H
s=
::= =
— —
S=S=
■:.=
J '
11
11! '.
v,
! '
-LLL
'=='=
' ' '
11.
1
/
R t /RLA5
3.0
2.5
2.0
1.5
1.0
0.5
10-'
R t /RLA5
3.0
2.5
2.0
1.5
1.0
0.5
10-
*Markof Schlumberger
© Schlumberger
10°
10'
10 2 10 3
RLA5/R m
Standoff = 0.5 in.
10"
10=
10 6
i
1
1
1
1
1
1
1
/
''
1
.'
i
r
w
-■-
i = i"iS
■m -
*T
»
■«
*?!*.--~-~:~i"~Y:';Y?:
" -■.";"
..-
,T
■,— ■-
5 in.
6 in.
8 in.
9 in.
10 in.
1 2 in.
14 in.
16 in.
18 in.
20 in.
22 in.
10°
10'
10 2 10 3
RLA5/R m
Standoff =1.5 in.
10 4
10=
10 6
\
!
1
1
I
/
1
1
/
/
/
/
/
..
*>''
^f
±?
VJW'tt
fl
. J -
t*fl
-
r
r.T-r.-
10°
10'
10 2
10 3
10'
10=
10 6
RLA5/R m
Purpose effects. RLA5 is the apparent resistivity from computed focusing
This chart is used to similarly to Chart RL1-2 to correct HRLA High- mode 5.
Resolution Laterolog Array resistivity for borehole and drilling mud
114
< ► Back to Contents
Resistivity Laterolog — LWD
Schlumberger
GeoSteering* Bit Resistivity — 6.75-in. Tool
Borehole Correction — Open Hole
RLI-20
*Markof Schlumberger
© Schlumberger
R t /R a
R t /R a
1 f
1.1
1.0
0.9
0.8
0.7
0.5
n
24-in. bit
18-in. bit
12-in. bit
1
1 ?
o- 2
1
0-' 10°
10' 10 2
R a /R m
10 3
10" 10 5
1.1
1.0
0.9
0.8
0.7
0.6
OR
24-in. bit
18-in. bit
12-in. bit
1
o- 2
1
0"' 10°
10' 10 2
R a /R m
10 3
10 4 1
D 5
Purpose
This chart is used to derive the borehole correction for the GeoSteering
bit-measured resistivity. The bit resistivity corrected to the true
resistivity (Rt) is then used in the calculation of water saturation.
Description
Enter the chart on the x-axis with the ratio of the bit resistivity and
mud resistivity (R a /R m ) at formation temperature. Move upward to
intersect the appropriate bit size. Move horizontally left to intersect
the correction factor on the y-axis. Multiply the correction factor by
the R a value to obtain Rt. Charts RL1-21, RL1-23, and RL1-24 are simi-
lar to Chart RLI-20 for different tools and bit sizes.
Chart RL1-22 differs in that it is for reaming-down mode as
opposed to drilling mode.
Back to Contents
115
Resistivity Laterolog-LWD
GeoSteering* arcVISION675* Resistivity— 6.75-in. Tool
Borehole Correction — Open Hole
Schlumberger
RLI-21
1.2
Rt/R.
Rt/Ra
1.2
1.1
I.U
0.9
0.8
07
OR
24-in. bit
18-in. bit
12-in. bit
10- 2 10-' 10° 10 1 10 2 10 3 10 4 10 5
R a /R m
1.1
1 n
(19
OR
07
OR
■)
4-in. bit
OR
1
1
8-in. bit
2-in. bit
10" :
10" 1 10° 10 1 10 2 10 3 10 4 10 5
*Markof Schlumberger
© Schlumberger
Purpose
This chart is used similarly to Chart RL1-20 to derive the borehole
correction for the GeoSteering bit-measured arcVISION675
resistivity.
116
< ►
Back to Contents
Resistivity Laterolog — LWD
Schlumberger
GeoSteering* Bit Resistivity in Reaming Mode — 6.75-in. Tool
Borehole Correction — Open Hole
RLI-22
1.5
1.4
1.3
1.2
1.1
Rt/R. i.o
0.9
0.8
0.7
0.6
05
Bit /
^^arcVISION*tool
10 -2 10-1 1Q 1f Jl 1Q 2 1 3 1Q4 10=
R a /Rm
*Markof Schlumberger
© Schlumberger
Purpose
This chart is used similarly to Chart RL1-20 to derive the borehole
correction for the GeoSteering bit-measured resistivity while ream-
ing down.
< ►
Back to Contents
117
Resistivity Laterolog — LWD
geoVISION* Resistivity Sub— 6.75-in. Tool
Borehole Correction — Open Hole
Schlumberger
RLI-23
Ring Resistivity (with 8V$-in. bit)
Rt/R.
10° 10 1 10 2 10 3 10 4 10=
R a /Rm
Medium Button Resistivity (with 8V2-in. bit)
Rt/R.
Be
re
h
Die
Jiame
i
13
te
r
/
ir
.)
/
I
/
•
/
2
1
1
I
U
.5
(
15
8 "5
10° 10 1 10 2 10 3 10 4 10=
Ra/Rm
Bit Resistivity (with 814-in. bit)
ROP to Bit Face = 4 ft
R,/R a
Bt
>re
nole
dia
ne
in
er (i
l.)
1
/
22 1
20
/
_ 18
■1 16
i\
__..
1
i
llL'lQ
B.5—
10° 10'
*Markof Schlumberger
© Schlumberger
10 2 10 3
R a /R m
10 4 10=
Rt/R.
Deep Button Resistivity (with 81/2-in. bit)
TTTTTl 1 — I llllll
Shallow Button Resistivity (with 8'/2-in. bit)
R./R.
Be
>r
9h
ole
diam
3t
ar(
n.)
/
1
1
10
/
9.5
/
9.2
/
5
9 1-
S.\)
10° 10 1 10 2 10 3 10 4 10 5
R./Rm
Bit Resistivity (with 81/2-in. bit)
ROP to Bit Face = 35 ft
R,/R.
E
>or(
jhok
di
an
le
ter
in.
1/
1/
1
/
22
\\\ ?
j
I
Ifi
"ffl —
— 1
4^
9 _
■TTT
^0-
— ; a.sw
10" 10'
10 2 10 3
R./R m
10 4 10 5
Purpose sub of the geoVISION 6.75-in. tool. The bottom row of charts
This chart is used similarly to Chart RL1-20 to derive the borehole specifies the bit readout point (ROP) to the bit face,
correction for the bit-measured resistivity from the GVR* resistivity
118
< ► Back to Contents
Resistivity Laterolog — LWD
geoVISION* Resistivity Sub— 8.25-in. Tool
Borehole Correction — Open Hole
Schlumberger
RLI-24
Ring Resistivity (with 1 2V4-in. bit)
R,/R a
Deep Button Resistivity (with 12!/4-in. bit)
10° 10'
10 2 10 3 10 4
R a /R m
Medium Button Resistivity (with 12!/4-in. bit)
R,/R a
B(
jre
iole
dia
1
ne1
/
er (
1
n.)
rl
/
1
J
1
7
16
/
1
5
/
14-
■13.5-
-19 9R-
10° 10 1
10 2 10 3
Ra/Rm
10 4 10=
Bit Resistivity (with 12V4-in. bit)
ROP to Bit Face = 4 ft
R,/R a
B
Dre
rrrm
iole
dia
m
Bt(
irl
n.)
26
/
J
/
24'
*
111
!0-
1
8
1R
14
m 12
2R
10" 10'
*Markof Schlumberger
© Schlumberger
10 2 10 3
Ra/Rm
10 4 10 5
Rt/Ra
Bort
h
ole
1 1 \l
diameter (in.)
/
/
/
/
20
19
/
8
'
/
17
Ifi'
IR
14
Tf 12.25 ""
10° 10'
10 2 103
Ra/Rm
10 4 10 5
Shallow Button Resistivity (with 1 2V4-in. bit)
R/Ra
E
e
lole
dif
rr
e
1
ter
f
in.)
\
1
4
/
j
1
13.;
1
1
13
J2.75
2.25
10° 10 1 10 2 10 3 10 4 10 5
R a /R m
Bit Resistivity (with 12/4-in. bit)
ROP to Bit Face = 35 ft
R,/R a
Borehole diameter (in.
Purpose sub of the geoVISION 8.25-in. tool. The bottom row of charts
This chart is used similarly to Chart RL1-20 to derive the borehole specifies the bit readout point (ROP) to the bit face,
correction for the bit-measured resistivity from the GVR* resistivity
< ►
Back to Contents
119
Resistivity Laterlog — LWD
GeoSteering* Bit Resistivity — 6.75-in. Tool
Distance Out of Formation — Open Hole
Schlumberger
RLI-25
Distance (ft)
600
500
400
300
200
100
lOohm-
lOOohrr
Iflnhm-
m/4° BUR
-m/4°BUR
m/5° BUR
100ohm-m/5°BUR
10ohm-m/10°BUR
/$
/ *
10
12
Dip angle I
*Markof Schlumberger
© Schlumberger
Purpose
This chart is used to calculate the distance the GeoSteering bit must
travel to return to the target formation.
Description
When drilling is at very high angles from vertical, the bit may wander
out of formation. If this occurs, how far the bit must travel to get
back into the formation must be determined.
Enter the chart with the known dip angle of the formation on
the x-axis. Move upward to intersect the appropriate "buildup rate"
(BUR) curve. Move horizontally left from the intersection point to
the y-axis and read the distance back into the formation.
Example
Given:
Find:
Answer:
Formation dip angle = 6° formation resistivity during
drilling = 10 ohm-m, and buildup rate = 4°.
Distance to return to the target formation.
Enter the chart at 6° on the x-axis. Move upward to the
10 ohm-m/4° BUR curve. Move horizontally left to the
y-axis to read approximately 290 ft.
120
Back to Contents
Resistivity Laterolog — Wireline
CHFR* Cased Hole Formation Resistivity Tool
Cement Correction — Cased Hole
Schlumberger
RLI-50
CHFR Cement Correction Chart (4.5-in.-0D casing)
1.6
1.4
No cement
3.5 in.
3.75 in.
1.2
1.5 in.
3 in.
5 in.
-•-
■•
.
••-
•
— *
i —
. -•
1.0
Rt/Rchfr °' 8
0.6
\ i
i
1
i
— «
►-
-O 1
*—
/
i
It
/
/
/
9«^==^
— »
►-
-<» — <
» —
"•—
'
/
/
/
i ,
i
i
i
i
i
0.4
J i
i
i
i
+ :
i
m
i
i
0.2
T i
1 i
1 i
/ •
m
i
i
i
t
io- 2
*Markof Schlumberger
© Schlumberger
10-'
10°
■'chfr/'*cem
10'
10 2
Purpose
This chart is used to correct the raw cased hole resistivity measure-
ment of the CHFR Cased Hole Formation Resistivity tool (R C Mr) for
the thickness of the cement sheath. The resulting value of true resis-
tivity (Rt) is used to calculate the water saturation.
Description
Enter the chart on the x-axis with the ratio of R C h& and the resistivity
of the cement sheath (R C em)- The value of R ce m is obtained with labo-
ratory measurements. Move upward to the appropriate cement
sheath thickness curve, which represents the annular space between
the outside of the casing and the borehole wall. Move horizontally
left to the y-axis and read the Rt/RcMt value. Multiply this value by
RcMr to obtain Rt.
Charts RL1-51 and RL1-52 are for making the correction in larger
casing sizes.
Back to Contents
121
Resistivity Laterolog — Wireline
CHFR* Cased Hole Formation Resistivity Tool
Cement Correction — Cased Hole
Schlumberger
RLI-51
CHFR Cement Correction Chart (7-in.-0D casing)
1.6
1.4
1.2
1.0
R,/Rch,r °- 8
0.6
0.4
0.2
10- 2
10-'
10°
■■chfr' ricem
\lo cement
3 5 in
3.75 in.
1.5 in.
3 in.
5 in.
1
-Z.'.
-•
-•
-
-
-
•
-II
•-
•
— H
4
i
— <
»—
ii i
>—
— <
/
/
>—
•
/
•/
(1 1
41
>
i
i
/
/
' /
/
•
/
/
t
/ f
i
' i
i
i
f /
*
/
i
/
i •
/ /
/
* i
*
10 1
10 2
*Markof Schlumberger
© Schlumberger
Purpose
This chart is used similarly to Chart RL1-50 to obtain the cased hole
resistivity of the CHFR Cased Hole Formation Resistivity tool cor-
rected for the thickness of the cement sheath in 7-in.-OD casing.
122
< ►
Back to Contents
Resistivity Laterolog — Wireline
CHFR* Cased Hole Formation Resistivity Tool
Cement Correction — Cased Hole
Schlumberger
RLI-52
1.6
CHFR Cement Correction Chart (9.625-in.-0D casing)
1.4
1.2
1.0
R,/Rch,r °- 8
0.6
0.4
0.2
No cement
0.5 in.
0.75 in.
1.5 in.
3 in.
5 in.
•
•
/
,'-
<b—
-•"
i — •
-•
i
1
— 1
►—
» 1
» —
/
>
* >
-it — <
» —
•
*
/
/ /
/ •
[ /
/
/
,' »
II
9 '
a
i >
*
1
*Markof Schlumberger
© Schlumberger
D- 2 10-' 10° 10 1 10 2
"chfr' "cem
Purpose
This chart is used similarly to Chart RL1-50 to obtain the cased hole
resistivity of the CHFR Cased Hole Formation Resistivity tool cor-
rected for the thickness of the cement sheath in 9.625-in.-OD casing.
< ►
Back to Contents
123
Resistivity Induction — Wireline
AIT* Array Induction Imager Tool
Operating Range — Open Hole
Schlumberger
Purpose
This chart is used to determine the limit of application for the AIT
Array Induction Imager Tool measurement in a salt-saturated borehole.
Description
When the AIT tool logs a large salt-saturated borehole, the 10- and
20-in. induction curves may well be unusable because of the large
conductive borehole. In a borehole with a diameter (dh) of 8 in.,
the 10- and 20-in. curve data are usable if Rt < 300R m . The ratio
of the true resistivity to the mud resistivity (Rt/R m ) is proportional
to (d h /8) 2 .
A general rule is that a 12-in. borehole must have a ratio of Rt/R m
< 133 to have usable shallow log data. Additional requirements are
that the borehole must be round and the AIT tool standoff is 2.5 in.
The value of Rt/R m is further reduced if the borehole is irregular or
the standoff requirement is not met.
Chart RInd-1 summarizes these requirements. The expected
values of Rt, R m , borehole size, and standoff size are entered to
accurately determine the usable resolution in a smooth hole. The
lower chart summarizes which AIT resistivity tools typically provide
the most accurate deep resistivity data.
Example: Salt-Saturated Borehole
Given: Borehole size = 10 in., Rt = 5 ohm-m, R m =
0.0135 ohm-m, and standoff (so) = 2.5 in.
Find: Which, if any, of the AIT curves are valid.
Answer: From the x-axis equation:
Enter the chart on the x-axis at 346 and move upward
to intersect Rt = 5 ohm-m on the y-axis. The intersection
point is in an error zone for which the shallow induction
curves are not valid even in a round borehole. The
deeper induction curves are valid only with a 2-ft or
larger vertical resolution.
The limits for the 1-, 2-, and 4-ft curves are integral to the chart.
As illustrated, a 1-ft 90-in. curve is not usable in a large salt-saturated
borehole. Also, under these conditions, the 1-, 2-, and 4-ft curves can-
not have the same resistivity response.
Example: Freshwater Mud Borehole
Given: Borehole size = 10 in., Rt = 5 ohm-m, R m = 0.135 ohm-m,
and standoff (so) = 1.5 in.
Which, if any, of the AIT curves are valid.
Rt/Rm = 37.0, (d h /8) 2 = (10/8) 2 = 1.5625, and (1.5/so) =
1.5/1.5 = 1. The resulting value from the x-axis equation
is 37.0 x 1.5625 x 1 = 57.9.
Enter the chart at 57.9 on the x-axis and intersect
Rt = 5 ohm-m on the y-axis. The intersection point is
within the limit of the 1-ft vertical resolution boundary.
All the AIT induction curves are usable.
Find:
Answer:
Rt
V R my
1.5
^10Yfl.5 A
0.0135
2.5
(370)(l.5625)(0.6)=346.
124
Back to Contents
Resistivity Induction — Wireline
AIT* Array Induction Imager Tool
Operating Range — Open Hole
Schlumberger
Rlnd-1
(ohm-m)
R,
(ohm-m)
innn
Limit of 4-ft logs
■■»■■"»• '"a
100
Limit of 1-ft logs
1
— range (compute standoff
.Salt-
saturated
10
method
torsmoot
n noies)
Freshwat
mud exan
?.r =j=
/ / borehole
/ example
i
/ on an iuy;
0.01 0.1
10 100 1,000 10,000 100,000
mm
10,000
inon
AIT 4-ft lir
nit
•
:AIT2-ft limit =
— y —
AIT 1 -ft li
100
Tilt
•
•
•
1
AIT
V> Al 1 and
fj=HHLA*=^
HRLA :
= tools —
^^^^
ifi tools ^/—
ll
0.01 0.1 1 10 100 1,000 10,000 100,000
R t /R m
*Markof Schlumberger
© Schlumberger
< ►
Back to Contents
125
Resistivity Induction — Wireline
AIT* Array Induction Imager Tool
Borehole Correction — Open Hole
Schlumberger
Introduction
The AIT tools (AIT-B, AIT-C, AIT-H, AIT-M, Slim Array Induction
Imager Tool [SAIT], Hostile Environment Induction Imager Tool
[HIT], and SlimXtreme* Array Induction Imager Tool [QAIT]) do not
have chartbook corrections for environmental effects. The normal
effects that required correction charts in the past (borehole correc-
tion, shoulder effect, and invasion interpretation) are now all made
using real-time algorithms for the AIT tools. In reality, the charts for
the older dual induction tools were inadequate for the complexity of
environmental effects on induction tools. The very large volume of
investigation required to obtain an adequate radial depth of investiga-
tion to overcome invasion makes the resulting set of charts too exten-
sive for a book of this size. The volume that affects the logs can be tens
of feet above and below the tool. To make useful logs, the effects of the
volume above and below the layer of interest must be carefully removed.
This can be done only by either signal processing or inversion-based
processing. This section briefly describes the wellsite processing and
advanced processing available at computing centers.
Wellsite Processing
Borehole Correction
The first step of AIT log processing is to correct the raw data from
all eight arrays for borehole effects. Borehole corrections for the AIT
tools are based on inversion through an iterative forward model to
find the borehole parameters that best reproduce the logs from the
four shortest arrays — the 6-, 9-, 12-, and 15-in. arrays (Grove and
Minerbo, 1991). The borehole forward model is based on a solution
to Maxwell's equations in a cylindrical borehole of radius r with the
mud resistivity (R m ) surrounded by a homogeneous formation of
resistivity Rf. The tool can be located anywhere in the borehole, but
is parallel to the borehole axis at a certain tool standoff (so). The
borehole is characterized by its radius (r). In this model, the signal
in a given AIT array is a function of only these four parameters.
The four short arrays overlap considerably in their investigation
depth, so only two of the borehole parameters can be uniquely deter-
mined in an inversion. The others must be supplied by outside mea-
surements or estimates. Because the greatest sensitivity to the
formation resistivity is in the contrast between R m and Rf, no external
measurement is satisfactory for fitting to Rf. Therefore, Rf is always
solved for. This leaves one other parameter that can be determined.
The three modes of the borehole correction operation depend on
which parameter is being determined:
■ compute mud resistivity: requires hole diameter and standoff
■ compute hole diameter: requires a mud resistivity measurement
and standoff
■ compute standoff: requires hole diameter and mud resistivity
measurement.
Because the AIT borehole model is a circular hole, either axis
from a multiaxis caliper can be used. If the tool standoff is adequate,
the process finds the circular borehole parameters that best match
the input logs. Control of adequate standoff is important because
the changes in the tool reading are very large for small changes in
tool position when the tool is veiy close to the borehole wall. Near
the center of the hole the changes are very small. A table of rec-
ommended standoff sizes is as follows.
AIT Tool Recommended Standoff
Hole Size (in.)
Recommended Standoff (in.)
AIT-B, AIT-C, AIT-H, AIT-M, HIT
SAIT, QAIT
<5.0
-
0.5
5.0 to 5.5
-
1.0
5.5 to 6.5
0.5
1.5
6.5 to 7.75
1.0
2.0
7.75 to 9.5
1.5
2.5
9.5 to 11.5
2.0 + bowspring'
2.5
>11.5
2.5 + bowspring'
2.5
Note: Do not run AIT tools £
* Only for AIT-H tool
Each type of AIT tool requires a slightly different approach to
the borehole correction method. For example, the AIT-B tool requires
the use of an auxiliary R m measurement (Environmental
Measurement Sonde [EMS]) to compute R m or to compute hole
size by using a recalibration of the mud resistivity method internal
to the borehole correction algorithm. The Platform Express*
SlimAccess* and Xtreme* AIT tools have integral R m sensors that
meet the accuracy requirements for the compute standoff mode.
Log Formation
AIT tools are designed to produce a high-resolution log response
with reduced cave effect in comparison with the induction log deep
(ILD) in most formations. The log processing (Barber and Rosthal,
1991) is a weighted sum of the raw array data:
N z-z max * \
o log (z)=Z Z w I (i')o[ , )(.-4
where Oi g (z) is the output log conductivity in mS/m, a a w is the
skin-effect-corrected conductivity from the rath array, and the
weights (w) represent a deconvolution filter applied to each of the
raw array measurements. The log depth is z, and z' refers to the
distance above or below the log depth to where the weights are
applied. The skin effect correction consists of fitting the X-signal
to the skin-effect-error signal (Moran, 1964; Barber, 1984) at high
conductivities and the R-signal to the error signal at low conductivi-
126
Back to Contents
Resistivity Induction — Wireline
AIT* Array Induction Imager Tool
Borehole Correction — Open Hole
Schlumberger
ties, with the crossover occurring between 100 and 200 mS/m. The
use of the R-signal at low conductivities overcomes the errors in
the X-signal associated with the normal magnetic susceptibilities
of sedimentary rock layers (Barber et al, 1995).
The weights w in the equation can profit from further refine-
ment. The method used to compute the weights introduces a small
amount of noise in the matrix inversion, so the fit is about ±1% to
±2% to the defined target response. A second refinement filter is
used to correct for this error. The AIT wellsite processing sequence,
from raw, calibrated data to corrected logs, is shown in Fig. 1.
(Freedman and Minerbo, 1991, 1993; Zhang et al., 1994). Maximum-
Entropy Resistivity Log Inversion (MERLIN) processing (Barber et
al, 1999) follows Freedman and Minerbo (1991) closely, and that
paper is the basic reference for the mathematical formulation. The
problem is set up as the simplest parametric model that can fit the
data: a thinly layered formation with each layer the same thickness
(Fig. 2). The inversion problem is to solve for the conductivity of
each layer so that the computed logs from the layered formation
are the closest match to the measured logs.
R-signals only
A(H)IFC
L
1 >
28 channels ^B
28
(AIT-B,-C,and-D)^
16 channels
Borehole
► correction
or
16
(all others) A
V
Caliper j
►•
R m i
►■
Stanrinff ,
►■ '
14
or
Multichannel
signal
processing
and 2D
processing
Five depths
(10 to 90 in.)
G>
Skin
effect
correction
A
28
or
16
Five depths
(10 to 90 in.)
R-signals
X-signals
Figure 1. Block diagram of the real-time log processing chain from raw, calibrated array data to finished logs.
Exception
handling and
environmentally
compensated
log processing
AAA
R
Caliper
Raw BHC signals
.+. 10 in.
.+. 20 in.
->. 30 in.
->. 60 in.
->. 90 in.
There are only two versions of this processing — one for AIT-B,
AIT-C, and AIT-D tools and one for all other AIT tools (AIT-H, AIT-M,
SAIT, HIT, and QAIT) (Anderson and Barber, 1995). Only two ver-
sions are required because the tools were carefully designed with
the same coil spacings to produce the same two-dimensional (2D)
response to the formation.
Advanced Processing
Logs in Deviated Wells or Dipping Formations
The interpretation of induction logs is complicated by the large vol-
ume of investigation of these tools. The AIT series of induction tools
is carefully focused to limit the contributions from outside a rela-
tively thin layer of response (Barber and Rosthal, 1991). In beds
at high relative dip, the focused response cuts across several beds,
and the focusing developed for vertical wells no longer isolates the
response to a single layer. The effect of the high relative dip angle is
to blur the response and to introduce horns at the bed boundaries.
Maximum Entropy Inversion: MERLIN Processing
The maximum entropy inversion method was first applied by Dyos
(1987) to induction log data. For beds at zero dip angle, it has been
shown to give well-controlled results when applied to deep induction
(ID) and medium induction (IM) from the dual induction tool
Well path
Figure 2. The parametric model used in MERLIN inversion. All layers are the
same thickness, and the inversion solves for the conductivity of each layer
with maximum-entropy constraints.
Back to Contents
127
Resistivity Induction — Wireline
AIT* Array Induction Imager Tool
Borehole Correction — Open Hole
Schlumberger
The flow of MERLIN processing is shown in Fig. 3. The borehole-
corrected raw resistive and reactive (R- and X-) signals are used as
a starting point. The conductivity of a set of layers is estimated from
the log values, and the iterative modeling is continued until the logs
converge. The set of formation layer conductivity values is then con-
verted to resistivity and output as logs.
28 or 16 channels
Borehole-corrected
R- andX-signals
> Initial guess
lodel parameters
Invasion Processing
The wellsite interpretation for invasion is a one-dimensional (ID)
inversion of the processed logs into a four-parameter invasion model
(Rxo, Rt, ri, and n, shown in Fig. 4). The forward model is based on
the Born model of the radial response of the tools and is accurate for
most radial contrasts in which induction logs should be used. The
inversion can be run in real time. The model is also available in the
Invasion Correction module of the GeoFrame* Invasion 2 application,
which also includes the step-invasion model and annulus model (Fig. 4).
Step Profile
Forward model
Compute
Lagrangian
Computed log
Sensitivity
matrix
Update model
parameters
L
Distance from wellbore .
Formation
resistivity
profile
Exit
Write model
parameters
as log
Slope Profile
Rxo
>^ R,
— r,_>! N
r. i
I
I
Distance from wellbore .
Figure 3. Data flow in the MERLIN inversion algorithm. The output is the
final set of model parameters after the iterations converge.
Annulus Profile
Rxo
r 1
■"■ann
r„
R«
Figure 4. Parametric models used in AIT invasion processing. The slope
profile model is used for real-time processing; the others are available
at the computing centers. R xo = resistivity of the flushed zone, R t = true
resistivity, n = radius of invasion, R an n = resistivity of the annulus.
128
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Resistivity Induction — Wireline
AIT* Array Induction Imager Tool
Borehole Correction — Open Hole
Schlumberger
Another approach is also used in the Invasion 2 application mod-
ule. If the invaded zone is more conductive than the noninvaded
zone, some 2D effects on the induction response can complicate
the ID inversion. Invasion 2 conducts a full 2D inversion using a
2D forward model (Fig. 5) to produce a more accurate answer for
situations of conductive invasion and in thin beds.
Figure 5. The parametric 2D formation model used in Invasion 2.
References
Anderson, B., and Barber, T.: Induction Logging, Sugar Land, TX,
USA, Schlumberger SMP-7056 (1995).
Barber, T.D.: "Phasor Processing of Induction Logs Including
Shoulder and Skin Effect Correction," US Patent No. 4,513,376
(September 11, 1984).
Barber, T., et al: "Interpretation of Multiarray Induction Logs in
Invaded Formations at High Relative Dip Angles," The Log Analyst,
(May-June 1999) 40, No. 3, 202-217.
Barber, T., Anderson, B., and Mowat, G.: "Using Induction Tools to
Identify Magnetic Formations and to Determine Relative Magnetic
Susceptibility and Dielectric Constant," The Log Analyst
(July-August 1995) 36, No. 4, 16-26.
Barber, T., and Rosthal, R.: "Using a Multiarray Induction Tool to
Achieve Logs with Minimum Environmental Effects," paper SPE 22725
presented at the SPE Annual Technical Conference and Exhibition,
Dallas, Texas, USA (October 6-9, 1991).
Dyos, C. J.: "Inversion of the Induction Log by the Method of Maximum
Entropy," Transactions of the SPWLA 28th Annual Logging
Symposium, London, UK (June 29-July 2, 1987), paper T.
Freedman, R., and Minerbo, G.: "Maximum Entropy Inversion of the
Induction Log," SPE Formation Evaluation (1991), 259-267; also
paper SPE 19608 presented at the SPE Annual Technical Conference
and Exhibition, San Antonio, TX, USA (October 8-11, 1989).
Freedman, R., and Minerbo, G.: "Method and Apparatus for
Producing a More Accurate Resistivity Log from Data Recorded by an
Induction Sonde in a Borehole," US Patent 5,210,691 (January 1993).
Grove, G.R, and Minerbo, G.N.: "An Adaptive Borehole Correction
Scheme for Array Induction Tools," Transactions of the SPWLA 32nd
Annual Logging Symposium, Midland, Texas, USA (June 16-19,
1991), paper P.
Moran, J.H.: "Induction Method and Apparatus for Investigating
Earth Formations Utilizing Two Quadrature Phase Components of
a Detected Signal," US Patent No. 3,147,429 (September 1, 1964).
Zhang, Y-C, Shen, L., and Liu, C: "Inversion of Induction Logs Based
on Maximum Flatness, Maximum Oil, and Minimum Oil Algorithms,"
Geophysics (September 1994), 59, No. 9, 1320-1326.
Back to Contents
129
Resistivity Electromagnetic — LWD
arcVISI0N475* and ImPulse* 4 3 /4-in. Array
Resistivity Compensated Tools — 2 MHz
Borehole Correction — Open Hole
Purpose
This chart is used to determine the borehole correction applied
by the surface acquisition system to arcVISION475 and ImPulse
phase-shift (R ps ) and attenuation resistivity (R a d) curves on the
log. The value of Rt is used in the calculation of water saturation.
Description
Enter the appropriate chart for the borehole environmental condi-
tions and tool used to measure the various formation resistivities
with the either the uncorrected phase-shift or attenuation resistivity
value (not the resistivity shown on the log) on the x-axis. Move upward
to intersect the appropriate resistivity spacing line, and then move
horizontally left to read the ratio value on the y-axis. Multiply the
ratio value by the resistivity value entered on the x-axis to obtain Rt.
Charts REm-12 through REm-38 are used similarly to Chart
REm-11 for different borehole conditions and arcVISION* and
ImPulse tool combinations.
Schlumberger
Example
Given:
Find:
Answer:
Rps = 400 ohm-m (uncorrected) from arcVISION475
(2-MHz) phase-shift 10-in. resistivity, borehole size =
6 in., and mud resistivity (R m ) = 0.02 ohm-m at forma-
tion temperature.
Formation resistivity (Rt).
Enter the top left chart at 400 ohm-m on the x-axis
and move upward to intersect the 10-in. resistivity
curve (green).
Move left and read approximately 1.075 on the y-axis.
Rt = 1.075 x 400 = 430 ohm-m.
130
Back to Contents
Resistivity Electromagnetic — LWD
arcVISI0N475* and ImPulse* 4 3 /4-in. Array
Resistivity Compensated Tools — 2 MHz
Borehole Correction — Open Hole
Schlumberger
REm-11
2.0
R/Rp
arcVISI0N475 and ImPulse BoreholG Correction for 2 MHz, d h = 6 in., R m = 0.02 ohm-m
2.0
1 R
1.0
OR
R,/Ra
1 ")
\
1
'. "
y
J
OR
10-' 10° 10' 10 2 10 3
R ps (ohm-m)
10-' 10° 10' 10 2
R ad (ohm-m)
10 3
2.0
Rt/Rps
arcVISI0N475 and ImPulse Borehole Correction for 2 MHz, d h = 6 in., R m = 0.1 ohm-m
2.0
1 R
10
(1R
R,/Ra
1 R
1(1
0.R
10-' 10° 10' 10 2 10 3
R ps (ohm-m)
10-' 10° 10' 10 2
R ad (ohm-m)
10 3
2.0
R,/R P
arcVISI0N47R and ImPulse Borehole Correction for 2 MHz, d h = 6 in., R m = 1.0 ohm-m
2.0
1 R
10
OR
R,/Ra
1.R
1
f
OR
10- 1 10° 10 1 10 2 10 3
Rps (ohm-m)
10-' 10°
10 1
R ad (ohm-m)
10 2 10 3
*Markof Schlumberger
© Schlumberger
Resistivity spacing (in.) 10 16 22 28 34
< ►
Back to Contents
131
Resistivity Electromagnetic — LWD
arcVISI0N475* and ImPulse* 4 3 /4-in. Array
Resistivity Compensated Tools — 2 MHz
Borehole Correction — Open Hole
Schlumberger
REm-12
2.0
R t /R p ,
10- 1 10"
arcVISI0N475 and ImPulse Borehole Correction for 2 MHz, d h = 7 in., R m = 0.02 ohm-m
2.0
1 Ft
i n
OF
Pit/ Pi a
1.5
1.0
0.5
10'
R ps (ohm-m)
10 2
10 3
10- 1 10° 10' 10 2 10 3
R arl (ohm-m)
Rt/Rp
2.0
1.5
1.0
0.5
2.0
Rt/Rp
10-
10-' 10°
arcVISI0N475 and ImPulse Borehole Correction for 2 MHz, d h = 7 in., R m = 0.1 ohm-m
2.0
Rt/Rai
10'
Rps (ohm-m)
10 2
10 3
10-
10"
10'
R a „ (ohm-m)
arcVISI0N475 and ImPulse Borehole Correction for 2 MHz, d h = 7 in., R m = 1 .0 ohm-m
2.0
1 5
1 n
05
'
10° 10 1
R,,,. (ohm-m)
10 2
R,/R a
1.5
1.0
0.5
10 3
10-
1 5
1.0
05
10 2
10° 10' 10 2
R a(i (ohm-m)
10 3
10 3
*Markof Schlumberger
© Schlumberger
Resistivity spacing (in.)
10
16
■)■>
28
34
Purpose
This chart is used similarly to Chart REm-11 to determine the
borehole correction applied by the surface acquisition system
to arcVISION475 and ImPulse resistivity measurements. Uncorrected
resistivity is entered on the x-axis, not the resistivity shown on the log.
132
< ►
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Resistivity Electromagnetic — LWD
arcVISI0N475* and ImPulse* 4 3 /4-in. Array
Resistivity Compensated Tools — 2 MHz
Borehole Correction — Open Hole
Schlumberger
REm-13
2.0
Rt/Rp
10-' 10°
arcVISI0N475 and ImPulse Borehole Correction for 2 MHz, d h = 8 in., R m = 0.02 ohm-m
2.0
1 5
1
OF
■^s:
= !i ^
^
**;
^
Rt/Rai
1.5
1.0
0.5
1
10'
R ps (ohm-m)
10 2
10 3
10-
10°
10 1
10 2
10 3
Rt/Rp
2.0
1.5
1.0
0.5
10-
R t /R p
2.0
1.5
1.0
0.5
10"
10-' 10°
arcVISI0N475 and ImPulse Borehole Correction for 2 MHz, d h = 8 in., R m = 0.1 ohm-m
2.0
j j
^_,Jy
R t /R a
1.5
I
1 n
— -
L
]•/
05
10'
Rps (ohm-m)
10 2
10 3
arcVISI0N475 and ImPulse Borehole Correction for 2 MHz, d h = 8 in., R m = 1.0 ohm-m
2.0
R./R.
10'
R ps (ohm-m)
10 2
10 3
10-' 10° 10'
R ad (ohm-m)
10-' 10° 10 1 10 2
R ad (ohm-m)
10 2
10 3
1.5
in
1
05
10 3
*Markof Schlumberger
© Schlumberger
Resistivity spacing (in.) 10 16
22 28
34
Purpose
This chart is used similarly to Chart REm-11 to determine the
borehole correction applied by the surface acquisition system
to arcVISION475 and ImPulse resistivity measurements. Uncorrected
resistivity is entered on the x-axis, not the resistivity shown on the log.
< ►
Back to Contents
133
Resistivity Electromagnetic — LWD
arcVISI0N475* and ImPulse* 4 3 /4-in. Array
Resistivity Compensated Tools — 2 MHz
Borehole Correction — Open Hole
Schlumberger
REm-14
2.0
R t /R p
arcVISI0N475 and ImPulse Borehole Correction for 2 MHz, d h = 10 in., R m = 0.02 ohm-m
2.0
1 R
/
1 n
or
■"■■^
S5
-5::
^
5
fc
N
R t /R a
1 R
10
OR
10-' 10° 10 1 10 2
R DS (ohm-m)
10 3
10- 1 10° 10' 10 2
R ad (ohm-m)
10 3
2.0
Rt/Rp
Rt/Rp
2.0
1.5
1.0
0.5
arcVISI0N475 and ImPulse Borehole Correction for 2 MHz, d h = 10 in., R m = 0.1 ohm-m
2.0
1 5
/
1
i n
05
R,/Ra
1.5
1.0
0.5
10-' 10"
10 1 10 2
R ps (ohm-m)
10 3
10-' 10°
arcVISI0N475 and ImPulse Borehole Correction for 2 MHz, d h = 10 in., R m = 1.0 ohm-m
2.0
10'
R ps (ohm-m)
10 2
1.5
R,/R a
1.0 =
0.5
10 3
10-
10° 10 1
R ad (ohm-m)
10-' 10° 10' 10 2 10 3
R ad (ohm-m)
I
_Jf
10 2 10 3
*M a rkof Schlumberger
© Schlumberger
Resistivity spacing (in.) 10 16 22 28 34
Purpose
This chart is used similarly to Chart REm-11 to determine the
borehole correction applied by the surface acquisition system
to arcVISION475 and ImPulse resistivity measurements. Uncorrected
resistivity is entered on the x-axis, not the resistivity shown on the log.
134
< ►
Back to Contents
Resistivity Electromagnetic — LWD
arcVISION675* 6 3 /4-in. Array Resistivity Compensated Tool— 400 kHz
Borehole Correction — Open Hole
Schlumberger
REm-15
R,/R P
2.0
1.5
1.0
0.5
arcVISI0N675 Borehole Correction for 400 kHz, d h = 8 in., R m = 0.02 ohm-m
2.0
/
•«!!53
5 ==
^
R,/R a
1.5
1.0
0.5
10-' 10° 10 1 10 2
R ps (ohm-m)
10 3
I
J
10-' 10° 10 1 10 2 10 3
R arl (ohm-m)
Rt/R„
2.0
1.5
1.0
0.5
arcVISION675 Borehole Correction for 400 kHz, d h = 8 in., R m = 0.1 ohm-m
2.0
1
-«£
11/
R,/Ra
1 5
1.0
..^
^
/
05
10-' 10° 10 1 10 2
Rps (ohm-m)
10 3
10-' 10° 10 1 10 2
R ari (ohm-m)
10 3
2.0
R/Rps
1.5
1.0
0.5
10- 1 10°
arcVISI0N675 Borehole Correction for 400 kHz, d h = 8 in., R m = 1 .0 ohm-m
2.0
R t /R a
1.5
1.0
0.5
....>
/
10 1 10 2
10 3
10-
R ps (ohm-m)
10° 10 1 10 2
R ari (ohm-m)
10 3
*Markof Schlumberger
© Schlumberger
Resistivity spacing (in.) 16 22 28 34 40
Purpose
This chart is used similarly to Chart REm-11 to determine the
borehole correction applied by the surface acquisition system
to arcVISION675 resistivity measurements. Uncorrected resistivity
is entered on the x-axis, not the resistivity shown on the log.
< ►
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135
Resistivity Electromagnetic — LWD
arcVISION675* 6 3 /4-in. Array Resistivity Compensated Tool— 400 kHz
Borehole Correction — Open Hole
Schlumberger
REm-16
2.0
Rt/Rp
arcVISION675 Borehole Correction for 400 kHz, d h = 10 in., R m = 0.02 ohm-m
2.0
1 "i
1 n
05
R,/Ra
1.5
1.0
0.5
10-' 10° 10' 10 2 10 3
R ps (ohm-m)
10-' 10° 10' 10 2 10 3
2.0
Rt/Rp
arcVISI0N675 Borehole Correction for 400 kHz, d h = 10 in., R m = 0.1 ohm-m
2.0
1 5
il
1.0
— -
->
{
f ;
05
R,/Ra
10- 1 10° 10' 10 2 10 3
Rps (ohm-m)
1 5
lj
1
,,^
;
I 1
05
10- 1 10° 10 1 10 2 10 3
R ad (ohm-m)
2.0
Rt/Rp
1 5
1.0
05
arcVISI0N675 Borehole Correction for 400 kHz, d h = 10 in., R m = 1.0 ohm-m
2.0
Rt/R.
1 5
I
1 n
..J
1
05
— .
:: ~<
\
10- 1 10° 10' 10 2
Rps (ohm-m)
10 3
10-' 10° 10 1 10 2 10 3
*Markof Schlumberger
© Schlumberger
Resistivity spacing (in.) 16 22 28 34 40
Purpose
This chart is used similarly to Chart REm-11 to determine the
borehole correction applied by the surface acquisition system
to arcVISION675 resistivity measurements. Uncorrected resistivity
is entered on the x-axis, not the resistivity shown on the log.
136
< ►
Back to Contents
Resistivity Electromagnetic — LWD
arcVISION675* 6 3 /4-in. Array Resistivity Compensated Tool— 400 kHz
Borehole Correction — Open Hole
Schlumberger
REm-17
2.0
Rt/Rp
arcVISION675 Borehole Correction for 400 kHz, d h = 12 in., R m = 0.02 ohm-m
2.0
1 5
in
OR
=a
"tf
t S
^
\
V
Rt/Ra
1 F
I
in
/
1
/
OF
"°==:
•U
~^
^N
\
10-' 10° 10 1
Rps (ohm-m)
10 2
10 3
10-' 10" 10' 10 2
Rad (ohm-m)
10 3
Rt/Rp
2.0
1.5
1.0
0.5
2.0
Rt/Rp
10-' 10°
arcVISION675 Borehole Correction for 400 kHz, d h = 12 in., R m = 0.1 ohm-m
2.0
/ /
:: yy'
"~~~T^\-
Rt/Rai
10'
Rps (ohm-m)
102 1Q3
1.5
1.0
05
arcVISI0N675 Borehole Correction for 4H0 kHz, d h = 1 2 in., R m = 1.0 ohm-m
2.0
10-1 100 ioi
Rps (ohm-m)
Rt/R.
10 2 10 3
10-'
10"
10'
Rad (ohm-m)
15
J
in
--€
^
I
05
10-1 100 101 102
R ad (ohm-m)
10 3
1 5
1
1.0
>
I
1
05
102 1Q3
*Markof Schlumberger
© Schlumberger
Resistivity spacing (in.) 16 22 28 34 40
Purpose
This chart is used similarly to Chart REm-11 to determine the
borehole correction applied by the surface acquisition system
to arcVISION675 resistivity measurements. Uncorrected resistivity
is entered on the x-axis, not the resistivity shown on the log.
< ►
Back to Contents
137
Resistivity Electromagnetic — LWD
arcVISION675* 6 3 /4-in. Array Resistivity Compensated Tool— 400 kHz
Borehole Correction — Open Hole
Schlumberger
REm-18
2.0
R t /R p
arcVISION675 BoreholG Correction for 400 kHz, d h = 14 in., R m = 0.02 ohm-m
2.0
1 5
in
OF
R t /R a
1 s
1
i
1
rf=
^
^
1
1
/
I
OR
10-' 10° 10 1 10 2
R ps (ohm-m)
10 3
10-'
10° 10 1 10 2
R ad (ohm-m)
10 3
Rt/Rp
2.0
1.5
1.0
0.5
arcVISI0N675 Borehole Correction for 400 kHz, d h = 14 in., R m = 0.1 ohm-m
2.0
f
/
'
R t /R ai
10-' 10° 10' 10 2
R ps (ohm-m)
10 3
1 5
\
1 n
f f
05
10-' 10° 10' 10 2 10 3
R ad (ohm-m)
2.0
R,/R P
1 5
\
1.0
05
arcVISI0N675 Borehole Correction for 400 kHz, d h = 14 in., R m = 1.0 ohm-m
2.0
10-' 10° 10' 10 2
R ps (ohm-m)
Rt/Ra
10 3
1.5 |
,.. _ Jl
HR
10-' 10° 10' 10 2
10 3
*Markof Schlumberger
© Schlumberger
Resistivity spacing (in.)
Ifi
22
28
34
40
Purpose
This chart is used similarly to Chart REm-11 to determine the
borehole correction applied by the surface acquisition system
to arcVISION675 resistivity measurements. Uncorrected resistivity
is entered on the x-axis, not the resistivity shown on the log.
138
< ►
Back to Contents
Resistivity Electromagnetic — LWD
arcVISION675* 6 3 /4-in. Array Resistivity Compensated Tool— 2 MHz
Borehole Correction — Open Hole
Schlumberger
REm-19
2.0
Rt/Rp
1 S
i n
or
arcVISI0N67B Borehole Correction for 2 MHz, d h = 8 in., R m = 0.02 ohm-m
2.0
R,/R a
1 R
i n
=
s== :
J
OF
10-' 10° 10 1
R„„ (ohm-m)
10 2
10 3
10-' 10° 10'
R ari (ohm-m)
10 2
10 3
2.0
R,/R P
1 R
1.0
OF
Hi^
^
^
io- 1
2.0
Rt/R„
10°
arcVISI0N67F Borehole Correction for 2 MHz, d h = 8 in., R m = 0.1 ohm-m
2.0
R,/Ra
10'
R ps (ohm-m)
10 2
10 3
10-
10°
10'
1.F
1 n
OR
arcVISI0N67F Borehole Correction for 2 MHz, d h = 8 in., R m = 1.0 ohm-m
2.0
10-' 10° 10 1
R n „ (ohm-m)
10 2
R,/Ra
10 3
1 F
J
10
ii
')
OF
10 2
10- 1 10° 10' 10 2
R ad (ohm-m)
10 3
1 R
1.0
OR
10 3
*Markof Schlumberger
© Schlumberger
Resistivity spacing (in.!
.16 22 28 34
.40
Purpose
This chart is used similarly to Chart REm-11 to determine the
borehole correction applied by the surface acquisition system
to arcVISION675 resistivity measurements. Uncorrected resistivity
is entered on the x-axis, not the resistivity shown on the log.
< ►
Back to Contents
139
Resistivity Electromagnetic — LWD
arcVISION675* 6 3 /4-in. Array Resistivity Compensated Tool— 2 MHz
Bed Thickness Correction — Open Hole
Schlumberger
REm-20
2.0
R/Rp
arcVISION675 BoreholG Correction for 2 MHz, d h = 10 in., R m = 0.02 ohm-m
2.0
1.5
1 n
OF
R,/Ra
1 5
I
1
on
•«^
^
5 k
10-' 10° 10' 10 2 10 3
R ps (ohm-m)
10-' 10° 10' 10 2 10 3
R ar] (ohm-m)
2.0
R t /R p
2.0
Rt/Rp
arcVISI0N675 Borehole Correction for 2 MHz, d h = 10 in., R m = 0.1 ohm-m
2.0
1 F
1
OF
r
=
T
^
ss
^
R,/Ra
1.5
1.0
0.5
111
M
10-' 10° 10' 10 2 10 3
Rps (ohm-m)
arcVISI0N675 Borehole Correction for 2 MHz, d h = 10 in., R m = 1.0 ohm-m
2.0
1 5
1.0
OR
R,/Ra
10-' 10° 10 1 10 2 10 3
Rps (ohm-m)
10-' 10° 10 1 10 2
R ar] (ohm-m)
10-' 10° 10' 10 2 10 3
R ari (ohm-m)
1 5
1.0
—'
/
0.5
10 3
*Markof Schlumberger
© Schlumberger
Resistivity spacing (in.) 16 22 28 34 40
Purpose
This chart is used similarly to Chart REm-11 to determine the
borehole correction applied by the surface acquisition system
to arcVISION675 resistivity measurements. Uncorrected resistivity
is entered on the x-axis, not the resistivity shown on the log.
140
< ►
Back to Contents
Resistivity Electromagnetic — LWD
arcVISION675* 6 3 /4-in. Array Resistivity Compensated Tool— 2 MHz
Borehole Correction — Open Hole
Schlumberger
REm-21
2.0
Rt/Rp
arcVISI0N675 Borehole CorrGction for 2 MHz, d h = 12 in., R m = 0.05 ohm-m
2.0
1 F
i n
OR
Rt/Ra
1 R
|
10
.--''
;
05
10-' 10" 10' 102 103
Rps (ohm-m)
10-' 10° 10' 10 2
Rad (ohm-m)
103
Rt/Rp
2.0
1.5
1.0
0.5
10-'
2.0
Rt/Rp
arcVISI0N675 Borehole Correction for 2 MHz, d h = 12 in., R m = 0.1 ohm-m
2.0
(
Rt/Ra
1.5
1.0
0.5
10" 10' 102 103
Rps (ohm-m)
1.5
/
10
05
arcVISI0N675 Boreholo Correction for 2 MHz, d h = 12 in., R m = 1.0 ohm-m
2.0
Rt/Ra
10-' 10° 10' 10 2 10 3
10-' 10°
10'
Rad (ohm-m)
_. _. 1
ML
10-' 10" 10' 102 103
Rad (ohm-m)
1.5
1
i n
0.5
102 1Q3
*Markof Schlumberger
© Schlumberger
Resistivity spacing (in.) 16 22 28 34 40
Purpose
This chart is used similarly to Chart REm-11 to determine the
borehole correction applied by the surface acquisition system
to arcVISION675 resistivity measurements. Uncorrected resistivity
is entered on the x-axis, not the resistivity shown on the log.
< ►
Back to Contents
141
Resistivity Electromagnetic — LWD
arcVISION675* 6 3 /4-in. Array Resistivity Compensated Tool— 2 MHz
Borehole Correction — Open Hole
Schlumberger
REm-22
2.0
Rt/Rp
arcVISI0N675 Borehole Correction for 2 MHz, d h = 14 in., R m = 0.02 ohm-m
2.0
1F
1 n
\
V
N,
OR
•*B
*a^S
■^
=
t
?
^
:v
:n
Rt/Ra
1F
1
OF
10- 1 10° 10' 10 2 10 3
R ps (ohm-m)
10-' 10° 10 1 10 2 10 3
R arl (ohm-m)
2.0
Rt/Rp
arcVISI0N675 Borehole Correction for 2 MHz, d h = 14 in., R m = 0.1 ohm-m
2.0
IF
i n
0.F
R,/R a
1 F
10
0.E
10-' 10° 10 1 10 2
Rps (ohm-m)
10 3
10-' 10" 10 1 10 2 10 3
R ar] (ohm-m)
Rt/Rps
2.0
1.F
1.0
0.E
arcVISI0N67E Borehole Correction for 2 MHz, d h = 14 in., R m = 1.0 ohm-m
2.0
-i=_j» ■ — ~-™^~===:::: z:
R,/Ra
1 F
10
-*
J
I
0.F
10-' 10° 10'
R n , (ohm-m)
10 2 10 3
10-' 10" 10' 10 2
R afi (ohm-m)
10 3
*Markof Schlumberger
© Schlumberger
Resistivity spacing (in.) 16 22 28 34 40
Purpose
This chart is used similarly to Chart REm-11 to determine the
borehole correction applied by the surface acquisition system
to arcVISION675 resistivity measurements. Uncorrected resistivity
is entered on the x-axis, not the resistivity shown on the log.
142
< ►
Back to Contents
Resistivity Electromagnetic — LWD
arcVISION825* 81/4-in. Array Resistivity Compensated Tool— 400 kHz
Borehole Correction — Open Hole
Schlumberger
REm-23
Rt/R„
2.0
1.5
1.0
0.5
10- 1
arcVISI0N825 Borehole Correction for 400 kHz, d h = 10 in., R m = 0.02 ohm-m
2.0
R,/Ra
1.5
1.0
0.5
J
I
10-'
10° 10' 10 2
R ad (ohm-m)
10 3
R t /R p
2.0
1.5
1.0
0.5
10-'
10"
arcVISI0N825 Borehole Correction for 400 kHz, d h = 10 in., R m = 0.1 ohm-m
2.0
R t /R a
1.5
1.0
0.5
10'
R ps (ohm-m)
10 2
10 3
10-
10° 10 1 10 2
R ari (ohm-m)
10 3
2.0
R,/R P
arcVISI0N825 Borehole Correction for 400 kHz, d h = 10 in., R m = 1.0 ohm-m
2.0
1 5
1 n
05
R,/Ra
1 5
i n
05
,,!a ^
^
1
^
*
>s
10-' 10° 10 1 10 2 10 3
Rps (ohm-m)
10- 1
10° 10'
10 2 10 3
*Markof Schlumberger
© Schlumberger
Resistivity spacing (in.)
16
22
98
34
40
Purpose
This chart is used similarly to Chart REm-11 to determine the
borehole correction applied by the surface acquisition system
to arcVISION825 resistivity measurements. Uncorrected resistivity
is entered on the x-axis, not the resistivity shown on the log.
< ►
Back to Contents
143
Resistivity Electromagnetic — LWD
arcVISION825* 8!/4-in. Array Resistivity Compensated Tool— 400 kHz
Bed Thickness Correction — Open Hole
Schlumberger
REm-24
2.0
arcVISION825 Borehole Correction for 400 kHz, d h = 12 in., R
?n
„ = 0.02 ohm-m
1.5
R,/R ps
1.0
05
1.5
/
R t /R ad
1
,^
I
'l
OR
=:: ^
^
^
:\
1(
2.0
H
10"
Rps
10'
(ohm-m)
arcVISI0N82
10 2 10 3 io- 1
5 Borehole Correction for 400 kHz, d h = 12 in., F
20
10° 10 1
R ad (ohm-m)
m = 0.1 ohm-m
10 2
IO 3
1.5
R t /R ps
1.0
0.5
Y
)
/
1.5
I
^
4:.
1
/
R t /R ad
1
-■=:
...^
<f
/
0.5
; x
X
\
1(
2.0
)-'
10°
Rps
10 1
(ohm-m)
arcVISION82
10 2
5 Borehole Co
10 3 10-'
rrection for 400 kHz, d h = 12 in., F
?n
10" 10'
R ad (ohm-m)
m = 1.0 ohm-m
10 2
10 3
1.5
Rt/Rps
1.0
05
1.5
Rt/Rad
1
5
■«^5
^
; ';
k
fc
s
1
]-'
10"
Rps
10'
(ohm-m)
10 2
10 3 io- 1
10"
Rad
10'
ohrr
-m)
10 2
10 3
F
psistiwity sparing (in) 1fi 2? 2R 34 40
© Schlumberger
Purpose
This chart is used similarly to Chart REm-11 to determine the
borehole correction applied by the surface acquisition system
to arcVISION825 resistivity measurements. Uncorrected resistivity
is entered on the x-axis, not the resistivity shown on the log.
144
< ►
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Resistivity Electromagnetic — LWD
arcVISION825* 8!/4-in. Array Resistivity Compensated Tool— 400 kHz
Borehole Correction — Open Hole
Schlumberger
REm-25
R,/R P
2.0
1.5
1.0
0.5
10-'
10°
arcVISION825 Borehole Correction for 400 kHz, d h = 14 in., R m = 0.02 ohm-m
2.0
R,/R a
10'
R ps (ohm-m)
10 2 10 3
10" 10 1 10 2
R ad (ohm-m)
10 3
Rt/Rp
2.0
1.5
1.0
0.5
arcVISI0N825 Borehole Correction for 400 kHz, d h = 14 in., R m = 0.1 ohm-m
2.0
I
R«/Ra
1.5
1.0
0.5
10- 1 10° 10' 10 2
R ps (ohm-m)
10 3
10-
10° 10 1 10 2
R ad (ohm-m)
10 3
2.0
Rt/Rp
arcVISI0N825 Borehole Correction for 400 kHz, d h = 14 in., R m = 1.0 ohm-m
2.0
1 5
i n
05
10- 1 10° 10 1 10 2
R ps (ohm-m)
R«/Ra
1.5
1.0
0.5
10 3
10-' 10° 10 1 10 2
R ad (ohm-m)
10 3
*Markof Schlumberger
© Schlumberger
Resistivity spacing (in.) 16 22 28 34 40
Purpose
This chart is used similarly to Chart REm-11 to determine the
borehole correction applied by the surface acquisition system
to arcVISION825 resistivity measurements. Uncorrected resistivity
is entered on the x-axis, not the resistivity shown on the log.
< ►
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145
Resistivity Electromagnetic — LWD
arcVISION825* 81A-in. Array Resistivity Compensated Tool— 400 kHz
Borehole Correction — Open Hole
Schlumberger
REm-26
R t /R„
2.0
1.5
1.0
0.5
arcVISION825 Borehole Correction for 400 kHz, d h = 18 in., R m = 0.02 ohm-m
2.0
/ ,
R t /R a
1.5
1.0
0.5
1/
1
k
10-' 10" 10' 102
R ps (ohm-m)
10 3
10-'
10° 10' 10 2
R ad (ohm-m)
10 3
2.0
Rt/Rps
arcVISION825 Borehole Correction for 400 kHz, d h = 18 in., R m = 0.1 ohm-m
2.0
1 5
1 n
05
Rt/Ra
1 5
i
I
1 n
U:
>i
I
1
05
10-' 10° 10 1 10 2
R ps (ohm-m)
10 3
10-' 10° 10' 10 2 10 3
R ad (ohm-m)
2.0
R t /R„
arcVISION825 Borehole Correction for 400 kHz, d h = 18 in., R m = 1.0 ohm-m
2.0
1 5
1 n
05
Rt/Ra
1.5
1.0
0.5
_nirik
10-' 10° 10' 10 2 10 3
Rps (ohm-m)
10-' 10° 10' 10 2
R ad (ohm-m)
10 3
*Markof Schlumberger
© Schlumberger
Resistivity spacing (in.)
1fi
22
28
34
40
Purpose
This chart is used similarly to Chart REm-11 to determine the
borehole correction applied by the surface acquisition system
to arcVISION825 resistivity measurements. Uncorrected resistivity
is entered on the x-axis, not the resistivity shown on the log.
146
< ►
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Resistivity Electromagnetic — LWD
arcVISION825* 8!/4-in. Array Resistivity Compensated Tool— 2 MHz
Borehole Correction — Open Hole
Schlumberger
REm-27
2.0
Rt/R„
10-'
10°
arcVISION825 BoreholG Correction for 2 MHz, d h = 10 in., R m = 0.02 ohm-m
2.0
1 R
1 n
OR
R,/Ra
1 R
1 n
OR
-^
?
s
x
\
10'
R ps (ohm-m)
10 2 10 3
10-' 10° 10' 10 2
R ad (ohm-m)
10 3
2.0
Rt/Rp
1 R
1 n
OR
10-
10"
arcVISI0N82R Borehole Correction for 2 MHz, d h = 10 in., R m = 0.1 ohm-m
2.0
Rt/Ra
1 R
J I
1
!
OR
10'
Rps (ohm-m)
10 2
10 3
10-
10° 10' 10 2
R ad (ohm-m)
10 3
Rt/Rp
2.0
1.5
1.0
0.5
10-'
10°
arcVISION825 Borehole Correction for 2 MHz, d h = 10 in., R m = 1.0 ohm-m
2.0
10'
R ps (ohm-m)
10 2
Rt/Ra
1.5
1.0
0.5
10 3
10-i 10 o 10 1
R ad (ohm-m)
10 2
- - - -f
10 3
*Markof Schlumberger
© Schlumberger
Resistivity spacing (in.)
Ifi
?■)
28
34
40
Purpose
This chart is used similarly to Chart REm-11 to determine the
borehole correction applied by the surface acquisition system
to arcVISION825 resistivity measurements. Uncorrected resistivity
is entered on the x-axis, not the resistivity shown on the log.
< ►
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147
Resistivity Electromagnetic — LWD
arcVISION825* 8!/4-in. Array Resistivity Compensated Tool— 2 MHz
Borehole Correction — Open Hole
Schlumberger
REm-28
2.0
arcVISI0N825 Borehole Correction for 2 MHz, d h = 12 in., R„
= 0.02ohm-rr
1.5
Rt/Rps
1.0
05
1.5
I
Rt/Rad
1
i
■ ~
T
»'■*,
^
>
^
s
OR
— >.
""^
N
^
11
2.0
)-'
10"
Rps
101
ohm-m)
arcVISION82
102 103 10-1
5 Borehole Correction for 2 MHz, d h = 12 in., R
20
10"
Rad
m = 0.1 ohm-m
10i
ohm-m)
102
103
1.5
Rt/Rps
1.0
05
1.5
1
|l
Rt/Rad
1
I! 5
1(
2.0
H
10»
Rps
10'
ohm-m)
arcVISION82
102
5 Borehole Cc
103 10-1
irrection for 2 MHz, d h = 12 in., R
20
10"
Rad
a = 1.0 ohm-m
10i
ohm-m)
102
103
1.5
Rt/Rps
1.0
05
1.5
|
Rt/Rad
- 1.0
^
5
^
--=:
^
\
\
1
h 1
10"
Rps
10'
ohm-m)
102
103 1Q-,
10"
Rad
10'
ohm
-m)
102
103
R
Rsistivity sparing (in) 1fi 22 28 3d 40
© Schlumberger
Purpose
This chart is used similarly to Chart REm-11 to determine the
borehole correction applied by the surface acquisition system
to arcVISION825 resistivity measurements. Uncorrected resistivity
is entered on the x-axis, not the resistivity shown on the log.
148
< ►
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Resistivity Electromagnetic — LWD
arcVISION825* 8!/4-in. Array Resistivity Compensated Tool— 2 MHz
Borehole Correction — Open Hole
Schlumberger
REm-29
2.0
Rt/Rp
arcVISI0N825 Borehole Correction for 2 MHz, d h = 14 in., R m = 0.02 ohm-m
2.0
1 5
i n
— — —
— —
05
..1^
^
^
^
^
^
:::n
Rt/Ra
1.5
1.0
0.5
7 r
10-' 10° 10' 102
R ps (ohm-m)
103
10-' 10 o ioi 102
R ad (ohm-m)
103
2.0
Rt/Rp
1 5
1
05
arcVISION825 Borehole Correction for 2 MHz, d h = 14 in., R m = 0.1 ohm-m
2.0
Rt/Ra
1 5
/
I
1 n
05
J
10-' 10° 10' 10 2
Rps (ohm-m)
10 3
10-' 100 ioi 102
R ad (ohm-m)
10 3
Rt/Rp
2.0
1.5
1.0
0.5
arcVISION825 Borehole Correction for 2 MHz, d h = 14 in., R m = 1.0 ohm-m
2.0
/
jy
w ~ ===:::::
Rt/Ra
1.5
1.0
0.5
-Tit 1
10-' 10° 10'
R DS (ohm-m)
102 1Q3
10-' 10° 10' 102
Rad (ohm-m)
103
*Markof Schlumberger
© Schlumberger
Resistivity spacing (in.) 16 22 28 34 40
Purpose
This chart is used similarly to Chart REm-11 to determine the
borehole correction applied by the surface acquisition system
to arcVISION825 resistivity measurements. Uncorrected resistivity
is entered on the x-axis, not the resistivity shown on the log.
< ►
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149
Resistivity Electromagnetic — LWD
arcVISION825* 8!/4-in. Array Resistivity Compensated Tool— 2 MHz
Borehole Correction — Open Hole
Schlumberger
REm-30
2.0
Rt/Rp
arcVISION825 Borehole Correction for 2 MHz, d h = 18 in., R m = 0.02 ohm-m
2.0
1 F
1 n
OR
Rt/Rp
1 F
1 n
OF
10-' 10" 10' 102 103
Rps (ohm-m)
10' 10" 10'
Rad (ohm-m)
102 1Q3
Rt/Rp
2.0
1.5
1.0
0.5
2.0
Rt/Rp
arcVISI0N825 Borehole Correction for 2 MHz, d h = 18 in., R m = 0.1 ohm-m
2.0
1
Rt/Rp
1 F
1
OF
10-' iqo iQi 1Q2
10 3
1 F
1
""*
DF
6
2
arcVISI0N825 Borehole Correction for 2 MHz, d h = 18 in., R m = 1.0 ohm-m
2.0
10-' ioo 101
R ps (ohm-m)
Rt/R
t/nps
102 1Q3
10-1 1Q0
10'
Rad (ohm-m)
10-' 10° 10' 10 2
Rad (ohm-m)
10 3
1 F
1
1
>-
— ,asi :
m
OF
102 1Q3
*Markof Schlumberger
© Schlumberger
Resistivity spacing (in.) 16 22 28 34 40
Purpose
This chart is used similarly to Chart REm-11 to determine the
borehole correction applied by the surface acquisition system
to arcVISION825 resistivity measurements. Uncorrected resistivity
is entered on the x-axis, not the resistivity shown on the log.
150
< ►
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Resistivity Electromagnetic — LWD
arcVISION900* 9-in. Array Resistivity Compensated Tool— 400 kHz
Borehole Correction — Open Hole
Schlumberger
REm-31
2.0
arcVISI0N900 Borehole Correction for 400 kHz, d h = 12 in., R
9 n
„ = 0.02 ohm-m
1.5
R t /R ps
1.0
05
1.5
/
'
Rt/Rad
1
J
/
y
OR
1(
2.0
H
10°
Rps
10'
(ohm-m)
arcVISI0N90
10 2 10 3 10-'
3 Borehole Correction for 400 kHz, d h = 12 in., F
?n
10° 10'
R ad (ohm-m)
m = 0.1 ohm-m
10 2
10 3
1.5
Rt/Rps
1.0
05
r
/
1.5
J
})
,..,-ssS
<
6
'j
Rt/Rad
1
— « s
A
/
5
1(
2.0
)-'
10°
Rps
10'
(ohm-m)
arcVISI0N90
10 2
] Borehole Cc
10 3 10-'
rrection for 400 kHz, d h = 12 in., F
10° 10'
R ad (ohm-m)
m = 1.0 ohm-m
10 2
10 3
1.5
Rt/Rps
1.0
05
1.5
Rt/Rad
1
^> 5
1
h'
10°
Rps
10'
(ohm-m)
10 2
10 3 10- 1
10°
Rad
w
ohm
-m)
10 2
10 3
F
lesistivity spacing (in.)
1R ?? n
■14 40
... , ,. .. .
© Schlumberger
Purpose
This chart is used similarly to Chart REm-11 to determine the
borehole correction applied by the surface acquisition system
to arcVISION900 resistivity measurements. Uncorrected resistivity
is entered on the x-axis, not the resistivity shown on the log.
< ►
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151
Resistivity Electromagnetic — LWD
arcVISION900* 9-in. Array Resistivity Compensated Tool— 400 kHz
Borehole Correction — Open Hole
Schlumberger
REm-32
Rt/Rp
arcVISION900 Borehole Correction for 400 kHz, d h = 15 in., R m = 0.02 ohm-m
2.0
Rt/R a
10 3
10 2 10 3
R t /R p
2.0
1.5
1.0
0.5
Rt/Rp
2.0
1.5
1.0
0.5
10-
arcVISI0N900 Borehole Correction for 400 kHz, d h = 15 in., R m = 0.1 ohm-m
2.0
R./R.
1.5
1.0
0.5
10-' 10° 10 1 10 2
R ps (ohm-m)
10 3
10-'
arcVISI0N900 Borehole Correction for 400 kHz, d h = 15 in., R m = 1.0 ohm-m
2.0
R,/R a
1.5
1.0
0.5
10° 10 1 10 2 10 3
R ps (ohm-m)
10-
10 3
10 3
*Markof Schlumberger
© Schlumberger
Resistivity spacing (in.) 16 22 28 34 40
Purpose
This chart is used similarly to Chart REm-11 to determine the
borehole correction applied by the surface acquisition system
to arcVISION900 resistivity measurements. Uncorrected resistivity
is entered on the x-axis, not the resistivity shown on the log.
152
< ►
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Resistivity Electromagnetic — LWD
arcVISION900* 9-in. Array Resistivity Compensated Tool— 400 kHz
Borehole Correction — Open Hole
Schlumberger
REm-33
2.0
Rt/Rp
arcVISI0N900 Borehole Correction for 400 kHz, d h = 18 in., R m = 0.02 ohm-m
2.0
1 5
/
/
i n
OR
Rt/Ra
1.5
1.0
0.5
/
1 1
M--
10-' 10" 10 1 10 2 10 3
R D s (ohm-m)
10-' 10" 10i 102
Rad (ohm-m)
10 3
2.0
Rt/Rp
2.0
Rt/Rp
arcVISION900 Borehole Correction for 400 kHz, d h = 18 in., R m = 0.1 ohm-m
2.0
1 5
/
1.0
05
Rt/Ra
1.5
1.0
0.5
10- 1 10" 10' 102
R ps (ohm-m)
103
arcVISI0N900 Borehole Correction for 400 kHz, d h = 18 in., R m = 1.0 ohm-m
2.0
1 5
1.0
05
Rt/Ra
10-1 io" 101 102
R DS (ohm-m)
10 3
10-i 10"
101
Rad (ohm-m)
10-' 10" 101 102
Rad (ohm-m)
10 3
1 5
1
"■■1
05
"'■^
l|
^
^
\
10 2 10 3
*Markof Schlumberger
© Schlumberger
Resistivity spacing (in.) 16 22 28 34 40
Purpose
This chart is used similarly to Chart REm-11 to determine the
borehole correction applied by the surface acquisition system
to arcVISION900 resistivity measurements. Uncorrected resistivity
is entered on the x-axis, not the resistivity shown on the log.
< ►
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153
Resistivity Electromagnetic — LWD
arcVISION900* 9-in. Array Resistivity Compensated Tool— 400 kHz
Borehole Correction — Open Hole
Schlumberger
REm-34
2.0
Rt/Rp
arcVISION900 BoreholG Correction for 400 kHz, d h = 22 in., R m = 0.02 ohm-m
2.0
1 5
1
OR
R t /R a
1 5
I
y
1
(15
10-' 10" 10' 102 103
R ps (ohm-m)
10-' 10" 10' 10 2
R ad (ohm-m)
10 3
Rt/Rp
2.0
1.5
1.0
0.5
Rt/Rp
2.0
1.5
1.0
0.5
arcVISI0N900 Borehole Correction for 400 kHz, d h = 22 in., R m = 0.1 ohm-m
2.0
/
//
/
i;
^
/
Rt/Ra
1 5
J
'
i n
i"'*^
£
i
/
05
10-' 10° 10 1 10 2 10 3
Rps (ohm-m)
arcVISI0N900 Borehole Correction for 400 kHz, d h = 22 in., R m = 1.0 ohm-m
2.0
1 '
' /
1.5
R,/Ra
1.0 &
0.5
10-' 10° 10'
R n<! (ohm-m)
10 2 10 3
10-
10" 10'
R ad (ohm-m
10-' 10° 10' 10 2 10 3
R ad (ohm-m)
10 3
*Markof Schlumberger
© Schlumberger
Resistivity spacing (in.) 16 22 28 34 40
Purpose
This chart is used similarly to Chart REm-11 to determine the
borehole correction applied by the surface acquisition system
to arcVISION900 resistivity measurements. Uncorrected resistivity
is entered on the x-axis, not the resistivity shown on the log.
154
< ►
Back to Contents
Resistivity Electromagnetic — LWD
arcVISION900* 9-in.Array Resistivity Compensated Tool— 2 MHz
Borehole Correction — Open Hole
Schlumberger
REm-35
2.0
Rt/Rp
arcVISION900 Borehole Correction for 2 MHz, d h = 1 2 in., R m = 0.02 ohm-m
2.0
1 Pi
i n
n5
■-•
— ■•■
"■'^
^
^
%
N
Rt/Ra
1 s
1 n
(15
— ■■!
"^
^
^
iiSN
10-' 10° 10' 10 2
R ps (ohm-m)
10 3
10-' 10° 10' 10 2
10 3
Rt/Rp
2.0
1.5
1.0
0.5
Rt/Rp
2.0
1.5
1.0
0.5
10-' 10"
arcVISI0N900 Borehole Correction for 2 MHz, d h = 12 in., R m = 0.1 ohm-m
2.0
Rt/Ra
1.5
1.0
0.5
10- 1
arcVISION900 Borehole Correction for 2 MHz, d h = 12 in., R m = 1.0 ohm-m
2.0
■f
\
Rt/Ra
1.5
1.0
0.5
10-' 10° 10' 10 2
Rps (ohm-m)
10 3
10-' 10° 10' 10 2
10° 10 1 10 2 10 3
1
;
^
■■"■^58=
\^
10 3
*Markof Schlumberger
© Schlumberger
Resistivity spacing (in.) 16 22 28 34 40
Purpose
This chart is used similarly to Chart REm-11 to determine the
borehole correction applied by the surface acquisition system
to arcVISION900 resistivity measurements. Uncorrected resistivity
is entered on the x-axis, not the resistivity shown on the log.
< ►
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155
Resistivity Electromagnetic — LWD
arcVISION900* 9-in. Array Resistivity Compensated Tool— 2 MHz
Borehole Correction — Open Hole
Schlumberger
REm-36
2.0
Rt/Rp
arcVISION900 BorGhole Correction for 2 MHz, d h = 1 R in., R m = 0.02 ohm-m
2.0
1 R
1
^^
OR
-=Sai
:=,^
^
4:
'1
^
S?
::x
Rt/Ra
1 R
/
1
OR
10-' 10° 10' 102
R ps (ohm-m)
103
10- 1 10° 10' 102
Rad (ohm-m)
103
2.0
Rt/Rp
1 R
i n
OR
Rt/Rp
2.0
1.R
1.0
0.R
arcVISI0N900 Borehole Correction for 2 MHz, d h = 1R in., R m = 0.1 ohm-m
2.0
Rt/Ra
1.R
1.0
0.R
1
10-' 10° 10' 10 2
Rps (ohm-m)
10 3
arcVISION900 Borehole Correction for 2 MHz, d h = 1R in., R m = 1.0 ohm-m
2.0
/
^
Rt/Ra
10' 10° 10'
Rps (ohm-m)
1Q2 1Q3
10-' 10° 10'
Rad (ohm-m)
10-' 10° 10' 102
R ad (ohm-m)
103
1 R
1 n
OR
■<=
=:::
; §
\
^v
10 2 1Q3
*Markof Schlumberger
© Schlumberger
Resistivity spacing (in.]
.16 22 28 34 40
Purpose
This chart is used similarly to Chart REm-11 to determine the
borehole correction applied by the surface acquisition system
to arcVISION900 resistivity measurements. Uncorrected resistivity
is entered on the x-axis, not the resistivity shown on the log.
156
< ►
Back to Contents
Resistivity Electromagnetic — LWD
arcVISION900* 9-in. Array Resistivity Compensated Tool— 2 MHz
Borehole Correction — Open Hole
Schlumberger
REm-37
2.0
Rt/Rp
arcVISI0N900 Borehole Correction for 2 MHz, d h = 18 in., R m = 0.02 ohm-m
2.0
Rt/Ra
1.5
1.0
0.5
/
^--
—
"^
^S
V
103
10-' 10" 10' 102 103
Rad (ohm-m)
2.0
Rt/Rp
1 5
1.0
05
arcVISI0N900 Borehole Correction for 2 MHz, d h = 18 in., R m = 0.1 ohm-m
2.0
Rt/Ra
1.5
1.0
0.5
/ / / /
j/jj
^"\
10-' 10" 10' 102
Rps (ohm-m)
103
10-' 10° 10' 102 103
Rad (ohm-m)
Rt/Rp
2.0
1.5
1.0
0.5
arcVISI0N900 Borehole Correction for 2 MHz, d h = 18 in., R m = 1.0 ohm-m
2.0
1
4
%
5=*
Rt/Ra
1.5
1.0
0.5
10-' 10" 10'
Rps (ohm-m)
102 1Q3
10' 10°
10'
Rad (ohm-m)
10 2 1Q3
*Markof Schlumberger
© Schlumberger
Resistivity spacing (in.) 16 22 28 34 40
Purpose
This chart is used similarly to Chart REm-11 to determine the
borehole correction applied by the surface acquisition system
to arcVISION900 resistivity measurements. Uncorrected resistivity
is entered on the x-axis, not the resistivity shown on the log.
< ►
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157
Resistivity Electromagnetic — LWD
arcVISION900* 9-in. Array Resistivity Compensated Tool— 2 MHz
Borehole Correction — Open Hole
Schlumberger
REm-38
Rt/Rp
2.0
1.5
1.0
0.5
arcVISION900 BorGhole Correction for 2 MHz, d h = 22 in., R m = 0.02 ohm-m
2.0
■<^
Rt/Ra
1.5
1.0
0.5
t
10-' 10" ioi 102
R ps (ohm-m)
103
10-1 ioo ioi 102
R ad (ohm-m)
103
2.0
Rt/Rp
1 fi
i
05
Rt/Rp
2.0
1.5
1.0
0.5
10-1
arcVISI0N900 Borehole Correction for 2 MHz, d h = 22 in., R m = 0.1 ohm-m
2.0
Rt/R a
1 5
/
)
1
*s2
^
4
Y
i
1
05
10-' 10" 10' 102
Rps (ohm-m)
10 3
arcVISION900 Borehole Correction for 2 MHz, d h = 22 in., R m = 1.0 ohm-m
2.0
/
h r
1.5
Rt/Ra
1.0 S
0.5
10° 10' 10 2 10 3
10-' 10°
10'
Rad (ohm-m
10-' io» ioi 102
R ad (ohm-m)
TO 3
103
*Markof Schlumberger
© Schlumberger
Resistivity spacing (in.) 16 22 28 34 40
Purpose
This chart is used similarly to Chart REm-11 to determine the
borehole correction applied by the surface acquisition system
to arcVISION900 resistivity measurements. Uncorrected resistivity
is entered on the x-axis, not the resistivity shown on the log.
158
< ►
Back to Contents
Resistivity Electromagnetic — LWD
arcVISION675* arcVISION825*, and arcVISION900*
Array Resistivity Compensated Tools — 400 kHz
Bed Thickness Correction — Open Hole
Purpose
This chart is used to determine the correction factor applied by the
surface acquisition system for bed thickness to the phase-shift and
attenuation resistivity on the logs of arcVISION675, arcVISION825,
and arcVISION900 tools.
Description
The six bed thickness correction charts on this page are paired for
phase-shift and attenuation resistivity at different values of true (Rt)
and shoulder bed (R s ) resistivity. Only uncorrected resistivity values
are entered on the chart, not the resistivity shown on the log.
Chart REm-56 is also used to find the bed thickness correction
applied by the surface acquisition system for 2-MHz arcVISION* and
ImPulse* logs.
Schlumberger
Example
Given:
Find:
Answer:
Rt/Rs = 10/1, R ps uncorrected = 20 ohm-m (34 in.), and
bed thickness = 6 ft.
Rt.
The appropriate chart to use is the phase-shift resistivity
chart in the first row, for Rt = 10 ohm-m and R s = 1 ohm-m.
Enter the chart on the x-axis at 6 ft and move upward
to intersect the 34-in. spacing line. The corresponding
value of Rt/Rp S is 1.6; Rt = 20 x 1.6 = 32 ohm-m.
< ►
Back to Contents
continued on next page
159
Resistivity Electromagnetic — LWD
arcVISION675* arcVISION825* and arcVISION900*
Array Resistivity Compensated Tools — 400 kHz
Bed Thickness Correction — Open Hole
Schlumberger
REm-55
arcVISI0N675, arcVISION825, and arcVISI0N900 400-kHz
Bed Thickness Correction for R t = 10 ohm-m and R s = 1 ohm-m at Center of Bed
?n
Pha
se-Shift Resistivity
1.5
1.0
0.5
n
Rt/Rps
2.0
Attenuation Resistivity
1.5
Rt/Rad 1.0
0.5
2 4 6 8 10 12 14 16
Bed thickness (ft)
2 4 6 8 10 12 14 16
Bed thickness (ft)
arcVISI0N675, arcVISI0N825, and arcVISI0N900 400-kHz
Bed Thickness Correction for R, = 1 ohm-m and R s =10 ohm-m at Center of Bed
2.0
Pha
;e-Shift Resistivity
1.5
Rt/Rps 1.0
0.5
/
*
S^
V
2.0
Attenuation Resistivity
1.5
Rt/Rad 1.0
0.5
^
^
^=
/
^r
2 4 6 8 10 12 14 16
Bed thickness (ft)
2 4 6 8 10 12 14 16
Bed thickness (ft)
*Markof Schlumberger
© Schlumberger
arcVISI0N675, arcVISION825, and arcVISI0N900 400-kHz
Bed Thickness Correction for R t = 100 ohm-m and R s =10 ohm-m at Center of Bed
2.0
Phase-Shift Resistivity
1.5
Rt/Rps 1.0
0.5
2 4 6 8 10 12 14 16
Bed thickness (ft)
Resistivity spacing (in.) 16 22 28 34 40
160
< ►
Back to Contents
Resistivity Electromagnetic — LWD
arcVISION* and ImPulse* Array Resistivity Compensated Tools — 2 MHz
Bed Thickness Correction — Open Hole
Schlumberger
REm-56
arcVISION and ImPulse 2-MHz Bed Thickness Correction for
R, = 10 ohm-m and R s =1 ohm-m at Center of Bed
2.0
Pha
se-Shift Resistivity
1.5
\
s.
R,/Rps 1.0
\Nj
^
^
0.5
2.0
Attenuation Resistivity
1.5
\^
v\
Rt/Rad i.o
^
^
0.5
2 4 6 8 10 12 14 16
Bed thickness (ft)
2 4 6 8 10 12 14 16
Bed thickness (ft)
arcVISION and ImPulse 2-MHz Bed Thickness Correction for
R, = 1 ohm-m and R, =10 ohm-m at Center of Bed
2.0
Pha
se-Shift Resistivity
1.5
R t /Rps i.o
0.5
2.0
Attenuation Resistivity
1.5
Rt/Rad 1-0
0.5
J
^
^
ss**
f
2 4 6 8 10 12 14 16
Bed thickness (ft)
2 4 6 8 10 12 14 16
Bed thickness (ft)
arcVISION and ImPulse 2-MHz Bed Thickness Correction for
R.= 100 ohm-m and R, =10 ohm-m at Center of Bed
2.0
Phas
;e-Shift Resistivity
1.5
Rt/Rps i.o
0.5
2.0
Attenuation Resistivity
1.5
^
k
Rt/Rad 10
^S
1
0.5
2 4 6 8 10 12 14 16
Bed thickness (ft)
2 4 6 8 10 12 14 16
Bed thickness (ft)
*Markof Schlumberger
© Schlumberger
Resistivity spacing (in.)
16
22
?R
34
40
< ►
Back to Contents
161
Resistivity Electromagnetic — LWD
arcVISION675* and ImPulse* Array Resistivity
Compensated Tools — 2 MHz and 16-in. Spacing
Dielectric Correction — Open Hole
Schlumberger
REm-58
I.60
8.55
i.50
8.45
I.40
Attenuation g 35
(dBJ
I.30
8.25
I.ZO
8.15
:.10
77777
° Dielectric assumption
e r = 5 + 108.5R- 035
*Markof Schlumberger
© Schlumberger
3 4
Phase shift!
Purpose
This chart is used to estimate the true resistivity (Rt) and dielectric
correction (e r ). Rt is used in water saturation calculation.
Description
Enter the chart with the uncorrected (not those shown on the log)
phase-shift and attenuation values from the arcVISION675 or
ImPulse resistivity tool. The intersection point of the two values is
used to determine Rt and the dielectric correction. Rt is interpolated
from the subvertical lines described by the dots originating at the
listed Rt values. The e r is interpolated from the radial lines originating
from the e r values listed on the left-hand side of the chart. Charts
REm-59 through REm-62 are used to determine Rt and e r at larger
spacings.
Example
Given: Phase shift = 2° and attenuation = 8.45 dB for 16-in.
spacing.
Find: Rt and e r .
Answer: Rt = 26 ohm-m and e r = 70 dB.
162
Back to Contents
Resistivity Electromagnetic — LWD
arcVISION675* and ImPulse* Array Resistivity
Compensated Tools — 2 MHz and 22-in. Spacing
Dielectric Correction — Open Hole
Schlumberger
REm-59
6.9
6.8
6.7
Attenuation
(dB)
6.6
6.5
6.4
6.3
TTT
////
° Dielectric assumption
e r = 5 + 108.5R" 035
*Markof Schlumberger
© Schlumberger
Phase shift!
Purpose
Charts REm-59 through REm-62 are identical to Chart REm-58
for determining Rt and e r at larger spacings of the arcVISION675
and ImPulse 2-MHz tools.
< ►
Back to Contents
163
Resistivity Electromagnetic — LWD
arcVISION675* and ImPulse* Array Resistivity
Compensated Tools — 2 MHz and 28-in. Spacing
Dielectric Correction — Open Hole
Schlumberger
REm-60
5.5
Attenuation
(dB)
5.4
5.3
5.2
5.1
5.0
4.9
4.8
o Dielectric assumption
E r = 5 + 108.5R- 035
*Markof Schlumberger
© Schlumberger
Phase shift!
Purpose
Charts REm-59 through REm-62 are identical to Chart REm-58
for determining Rt and e r at larger spacings of the arcVISION675
and ImPulse 2-MHz tools.
164
Back to Contents
Resistivity Electromagnetic — LWD
arcVISION675* and ImPulse* Array Resistivity
Compensated Tools — 2 MHz and 34-in. Spacing
Dielectric Correction — Open Hole
Schlumberger
REm-61
4.7
4.6
4.5
4.4
Attenuation 4.3
(dB)
4.2
4.1
4.0
3.9
77
77/
^7— '
"••:••:••:••■ / / /
VTT7TJJ
/A'/////
/ / /
////
V/////7
'//////
//////
/////
////
°Dielectric assumption
£ r = 5 + 108.5R-°- 35
*Markof Schlumberger
© Schlumberger
3 4 5
Phase shift (°)
Purpose
Charts REm-59 through REm-62 are identical to Chart REm-58
for determining Rt and e r at larger spacings of the arcVISION675
and ImPulse 2-MHz tools.
< ►
Back to Contents
165
Resistivity Electromagnetic — LWD
arcVISION675* and ImPulse* Array Resistivity
Compensated Tools — 2 MHz and 40-in. Spacing
Dielectric Correction — Open Hole
Schlumberger
REm-62
4.0
Attenuation
(dB)
3.9
3.8
3.7
3.6
3.5
3.4
3.3
3.2
3.1
°Dielectric assumption
e r = 5 + 108.5R- 035
*Markof Schlumberger
© Schlumberger
Phase shift (")
Purpose
Charts REm-59 through REm-62 are identical to Chart REm-58 for
determining Rt and e r at larger spacings of the arcVISION675 and
ImPulse 2-MHz tools.
166
Back to Contents
Resistivity Electromagnetic — LWD
arcVISION675* and ImPulse* Array Resistivity
Compensated Tools — 2 MHz with Dielectric Assumption
Dielectric Correction — Open Hole
Schlumberger
REm-63
3.5
10-'
Dielectric Effects of Standard Processed arcVISI0N675 or ImPulse Log
at 2 MHz with Dielectric Assumption
10°
10' 10 2
R„, (ohm-m)
10 3
3.0
Resistivity
spacing
16 in.
22 in
/
2.5
28 in.
34 in.
40 in.
/
/,
R,/R ps 2.0
e,
=
2e
r
1.5
°Dielect
e r = 5+1
ric a
08.5
SSL
R-°
m
35
at
n
1.0
0.5
e 2 =
0.5e r
10 4
3.5
3.0
2.5
R,/R ad 2.0
1.5
1.0
0.5
10-
*Markof Schlumberger
© Schlumberger
Resistivity
spacing
16 in.
22 in
28 in.
34 in.
40 in.
j.
e 2
=
0.
5e
r
D Dielect
e r = 5 +
'ic a
108.!
;su
>R-
mf
135
)ti
1
— —
-m
M
«
*
95
'^
^
^
1
?t
, = 2e r
HI
10°
10' 10 2
R art (ohm-m)
10 3
10 4
< ►
Back to Contents
167
Formation Resistivity — Wireline
Resistivity Galvanic
Invasion Correction — Open Hole
Schlumberger
Rt-1
(former Rint-1)
Purpose
The charts in this chapter are used to determine the correction for
invasion effects on the following parameters:
■ diameter of invasion (di)
■ ratio of flushed zone to true resistivity (R xo /Rt)
■ Rt from laterolog resistivity tools.
The Rxo/Rt and Rt values are used in the calculation of water
saturation.
Description
The invasion correction charts, also referred to as "tornado" or "but-
terfly" charts, assume a step-contact profile of invasion and that all
resistivity measurements have already been corrected as necessaiy
for borehole effect and bed thickness by using the appropriate chart
from the "Resistivity Laterolog" chapter.
To use any of these charts, enter the y-axis and x-axis with the
required resistivity ratios. The point of intersection defines di,
Rxo/Rt, and Rt as a function of one resistivity measurement.
Saturation Determination in Clean Formations
Either of the chart-derived values of Rt and R xo /Rt are used to find
values for the water saturation of the formation (Sw). The first of two
approaches is the S w - Arc hie (Swa), which is found using the Archie
saturation formula (or Chart SatOH-3) with the derived Rt value and
known values of the formation resistivity factor (Fr) and the resistiv-
ity of the water (R w ). The Sw- ratio (Swr) is found by using R xo /Rt and
Rmf/Rw as in Chart SatOH-4.
If Swa and Swr are equal, the assumption of a step-contact inva-
sion profile is indicated to be correct, and all values determined
(Sw, Rt, Rxo, and di) are considered good.
If Swa > Swr, either invasion is very shallow or a transition-type
invasion profile is indicated, and Swa is considered a good value for Sw.
If Swa < Swr, an annulus-type invasion profile may be indicated,
and a more accurate value of water saturation may be estimated
by using
1
'wA
V wR /
The correction factor of (Swa/Swr) 174 is readily determined from
the scale.
For more information, see Reference 9.
SwA'SwR
0.45
0.50
0.55
0.60
1
0.65 0.70
0.75
i
0.80
0.85
1
0.90
0.95
1.0
I
1
0.80
'' 1
0.85
1
i '| i ' i
0.90
r
1 ' 1
0.95
I
I
1.0
© Schlumberger
(S mA /S wR ) 4
168
Back to Contents
Formation Resistivity — Wireline
High-Resolution Azimuthal Laterolog Sonde (HALS)
Formation Resistivity and Diameter of Invasion — Open Hole
Schlumberger
Rt-2
Thick Beds, 8-in. Hole, R xo /R m = 10
10 3
10 2
HLLD/R X0
10 1
10°
10- 1
8 15
18
>o
2
2
24
28
3?
?f
n . -
^ 1 000
y
41
i
^
*
y
i / /
/
X
y'
y
y
?~T 7-
'
y
x
y
y
y
'
i / /
I , /
/
s
R,/R„
X
500
y
s
y
y
/
50
I l '
j 1 i i /
/
/
/
/•
y
y
y
y y
y
y\
y
y
An
V- , /
/
200
^
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' y
y ?"•
y
y
y
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— y-
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d, (in.
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* s
7S4J " u/ /
, ' >
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y
i'i^; -—
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© Schlumberger
10° 10' 10 2
HLLD/HLLS
Purpose
The resistivity values of HALS laterolog deep resistivity (HLLD),
HALS laterolog shallow resistivity (HLLS), and resistivity of the
flushed zone (R xo ) measured by the High-Resolution Azimuthal
Laterolog Sonde (HALS) are used with this chart to determine
values for diameter of invasion (di) and true resistivity (Rt).
Description
The conditions for which this chart is used are listed at the top. The
chart is entered with the ratios of HLLD/HLLS on the x-axis and
HLLD/Rxo on the y-axis. The intersection point defines dj on the
dashed curves and the ratio of Rt/R xo on the solid curves.
Example
Given:
Find:
Answer:
HLLD = 50 ohm-m, HLLS = 15 ohm-m, R xo = 2.0 ohm-m,
and R m = 0.2 ohm-m.
Rt and diameter of invasion.
Enter the chart with the values of HLLD/HLLS = 50/15 =
3.33 and HLLD/R X0 = 50/2 = 25.
The resulting point of intersection on the chart indicates
that Rt/R X o = 35 and di = 34 in.
Rt = 35 x 2.0 = 70 ohm-m.
Back to Contents
169
Formation Resistivity — Wireline
Schlumberger
High-Resolution Azimuthal Laterolog Sonde (HALS)
Formation Resistivity and Diameter of Invasion — Open Hole
Rt-3
Thick Beds, 8-in. Hole, R xo /R m = 10
10 3
10 2
HRLD/R X0
10 1
10°
10- 1
3 15
18
20
22
24
28
32
-9fi
7
s
1, 1 /
y
•a
/
•
/
y
i ^^-
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x
y
y
y-
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S
V45—
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1
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R t /R„
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5C
s
y
y
y
y
y
y
y
*
1
50
1,1 ' /
1.1 ' '
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© Schlumberger
10° 10 1 10 2
HRLD/HRLS
Purpose
The resistivity values of high- resolution deep resistivity (HRLD), high-
resolution shallow resistivity (HRLS), and R xo measured by the HALS
are used similarly to Chart Rt-2 to determine values for di and Rt.
Description
The conditions for which this chart is used are listed at the top. The
chart is entered with the ratios of HRLD/HRLS on the x-axis and
HRLD/Rxo on the y-axis. The intersection point defines di on the
dashed curves and the ratio of Rt/R X o on the solid curves.
170
Back to Contents
Formation Resistivity — LWD
geoVISION675* Resistivity
Formation Resistivity and Diameter of Invasion — Open Hole
Schlumberger
Rt-10
Ring, Deep, and Medium Button Resistivity (6.75-in. tool)
10
9
8
7
6
5
n r ing'''bni A
3
2
1
rVR m = 50
d h = 8.5 in.
1 R
IA
1.8 18
2.0
1 /
R/R
1.0 _^
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*Markof Schlumberger
© Schlumberger
1 2 3
Rring/Rbd
Purpose Example
This chart is used to determine the correction applied to the log Given:
presentation of Rt and di determined from geoVISION675 ring (Rring)
and deep (Rbd) and medium button (Rbm) resistivity values. pj n( j.
Description Answer:
Enter the chart with the ratios of R r i n g/Rbd on the x-axis and
Rrmg/Rbm on the y-axis. The intersection point defines di on the blue
dashed curves, Rt/Rring on the red curves, and Rt/R xo on the black
curves. Charts Rt-11 through Rt-17 are similar to Chart Rt-10 for
different tool sizes, configurations, and resistivity terms.
vnng
= 30 ohm-m, R X o/Rn
6 ohm-m.
50, Rbd = 15 ohm-m, and
Rt, di, and R xo .
Enter the chart with values of Rring/Rbd = 30/15 = 2 on
the x-axis and Rring/Rbm = 30/6 = 5 on the y-axis to find
di = 22.5 in., Rt/Rrmg = 3.1, and Rt/R X o = 50. From these
ratios, R t = 3.1 x 30 = 93 ohm-m and R xo = 93/50 =
1.86 ohm-m.
Back to Contents
171
Formation Resistivity — LWD
geoVISION675* Resistivity
Formation Resistivity and Diameter of Invasion — Open Hole
Schlumberger
Rt-11
Deep, Medium, and Shallow Button Resistivity (6.75-in. tool)
Rxo/R m = 50
Rbd/Rb S
30
20
10
9
8
7
6
5
4
3
2
d h = 8.5 in.
di
14-
_1.4_
-1.5
H t /H bd
1 ?
15
13
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/JL
S
'/^*
*^77
T^
n; >
1's
UI I \> J %
?/
3
l JiJk
f 2
1
1
1
1 2 3 4 5
"bJ"bm
*Markof Schlumberger
© Schlumberger
Purpose
This chart is used similarly to Chart Rt-10 to determine the
correction applied to the log presentation of Rt and di determined
from geoVISION675 deep (Rbd), medium (Rbm), and shallow
button (Rbs) resistivity values.
172
< ►
Back to Contents
Formation Resistivity — LWD
geoVISION675* Resistivity
Formation Resistivity and Diameter of Invasion — Open Hole
Schlumberger
Rt-12
Bit, Ring, and Deep Button Resistivity (6.75-in. tool) with ROP to Bit Face = 4ft
Rbit/Rb,
R„/R m = so
d h = 8.5 in.
9 c
.0
40
10
28 ,
-24
9
R t /h bit _
y •
^-34-
2 J
X /
/ •
H
1.E
/• ^
"K'
40
7
00
■>-
7-' ^
s
•
' •;
S / j
R
V
•'
^
■f /^
/ •
• >
bU
c
,
/
s^
*•
/
y
^ V
V i
/***'
100
5
20
^^
s
s
,' /a
^^
^^
s
*
*~50
4
t JuS
yS-
*"*V
/ y
y
30
^
/S
/
V
/^
/^m*"
y»
>
s
s
j/s
/^
20
3
18
/
•"V
^ ,
•v
15
i)f
/
•
/ <*■
-■v^X
/
■ /
x„,
in
fi^/A J?
*/
/
^4/
•
1.4 7
* '/jvf?^^
*^r /
S^t
/s
• ^_
7
?
z\rf^^
*
i
R //
//
/,
rl^A
S *
5
^\,
t %
ii />S
/ i
3
J/C
w
s
JS
1
wr£
7>
1
*Markof Schlumberger
© Schlumberger
Purpose
This chart is used similarly to Chart Rt-10 to determine the correc-
tion applied to the log presentation of Rt and di determined from
geoVISION675 R r i n g, bit (Rwt), and Rbd resistivity values.
Rbit/Rri
< ►
Back to Contents
173
Formation Resistivity — LWD
geoVISION675* Resistivity
Formation Resistivity and Diameter of Invasion — Open Hole
Schlumberger
Rt-13
Bit, Ring, and Deep Button Resistivity (6.75-in. tool) with ROPto Bit Face = 35 ft
20
10
9
8
7
6
rWr>bd _
b
4
3
2
1
R xo /R m = 50
d h - 8.5 in.
34
Z0 2.4
1 C
O 5[
)
Rt/R-
?a
7 «» / 1/
* /
I
1.
4
**>
y^,
7^ X A
100
7C
2
>*>
•
-70-
1 .
*^5
*r*
50
99 -**
r 4
•
*
f \
4?
^S
• .. : - ; '
*
*
j f
3
D
r *
2(
)
f^S
4t
20
rii
^*
j5' ; ^j
/»[/
/
.^v
•
•
15
/ -
■V
~?[ ]/
<W
+4
10
Rf/Rxn
18 /
v
'Ws
'v\V
//ft t
/^Jr
1
2 /
r /
f or
r\*
I
16
*
t *
>
E
I A
/th/f/t
i
3
i/
2
M*
1
*Markof Schlumberger
© Schlumberger
1 2 3456789 10 20
nbit'r»ring
Purpose
This chart is used similarly to Chart Rt-10 to determine the correc-
tion applied to the log presentation of Rt and di determined from
geoVISION675 R r i n g, Rbit, and Rbd resistivity values.
174
< ►
Back to Contents
Formation Resistivity — LWD
geoVISION825* 8 1 /4-in. Resistivity-at-the-Bit Tool
Formation Resistivity and Diameter of Invasion — Open Hole
Schlumberger
Rt-14
Ring, Deep, and Medium Button Resistivity (81/4-in. tool)
10
9
8
7
6
5
4
"ring' ''bm
3
2
1
Rxo/R m = 50
d h = 12.25 in.
1 R
— 1.8
2^
22-
.-
. *
01
00 ^~4^
«**
**■ V 1
3.0
di
1 A
*
**
<^
^
' s
*f**
• y'
>>• y
'26
20 <+
"***^ -^
*
/^ x
* S^
*
*
1 3 ^S "^
>*'** ^*
^r *»
X V
*
^r^
^/x
' '" ?~
^*s/
*
"** -^^
/ r 4 - >^
s /
^ '
30
19
£s"^ .
^
* >
rs>
100
/ 1 /
Sr
,*^.
if *
70
/ '/
/¥ f
7 <^
7' '
^ 30
18 /
//#
*£*<7j
/J''
'!////
• ' './—
y *N jfi
' on
MK
1.2 U.
/iff
<7><
zU
It' /
Iv / '
' /V/
'<T''t
/ * s
' 15
ff/i
M'/?/
y '^f'
j7 S'
10
1/
/i j/>//
i/* &•<.
/ jf
r'f —£'
' 7
ill/ jrb
Jr^jy'
111 / J^s
y / 5
16 1
w
'•
3
W 2
1
*Markof Schlumberger
© Schlumberger
1 2
"ring/ribd
Purpose
This chart is used similarly to Chart Rt-10 to determine the correc-
tion applied to the log presentation of Rt and di determined from
geoVISION825 R r i n g, Rbd, and Rbm resistivity values.
< ►
Back to Contents
175
Formation Resistivity — LWD
geoVISION825* 8 1 /4-in. Resistivity-at-the-Bit Tool
Formation Resistivity and Diameter of Invasion — Open Hole
Schlumberger
Rt-15
Deep, Medium, and Shallow Button Resistivity (8'/4-in. tool)
20
10
9
8
7
6
FL/Rbs 5
4
3
2
1
Rx /R m = 50
d h = 12.25 in.
19
R
/Rb
1 4
1 R
n
I ■■
IB
y '
>. ;
*
y
2.4
s
<
^
-"
•'
^ >
1.2.
y "■
/ ,
di
•
^
/>
■■ **
•V
/
*-*
• /
>>*»
.>
*
X
*•
«" >
**■
?7
jr**
24
16
tj
*
•
*
•
*
^
y*
•
•
y
^
/ ««*
70-
10
]
/i
•
••
^/
^
y
50
f '/
if
/
s
s
«* >■
/^
.*
V
/ •
/>
30
A /
il
/
A
/^
•
Jr *
*
/
X^
*
•>•
2 n
1.
1
• /
' 1
'Is'
*7
'/
7
i/R
XD
/ i
K J*
/.,
*
*
IE
h
/ijf
Si
i
lySP
f '
/•
/
i Jr7
'si's
•
7
/'/
v7
!A
ff
11/ 1
3
14
/ 1
r •
Y*
1
*Markof Schlumberger
© Schlumberger
1 2 3 4 E
Rbd'Hbm
Purpose
This chart is used similarly to Chart Rt-10 to determine the correc-
tion applied to the log presentation of Rt and di determined from
geoVISION825 Rbd, Rbm, and Rbs resistivity values.
176
< ►
Back to Contents
Formation Resistivity — LWD
geoVISION825* 8 1 /4-in. Resistivity-at-the-Bit Tool
Formation Resistivity and Diameter of Invasion — Open Hole
Schlumberger
Rt-16
Bit, Ring, and Doop Button Resistivity (8V4-in. tool) with ROP to Bit Face = 4 ft
10
9
8
7
6
5
4
r>bit/"bd
3
2
1
fUR m = 50
d h = 12.25 in.
^t/Rw
2.4:
3n
35
3U
i
V
^4U
2.0 .
J-50
1.8
*>"f**
*/
•
28
fs
""^ /
•
50
/ •
•
•/
/^//
^-•—1
^V
"-n/
^2/ 60
(J;
.6
*■ z
/
"V
"-*7*
/•
I
'HOOj
2b
' •
s
SJ
/d-
^^4
»
>5*
•
•
(^
sf
SJ^t
•
bU
1.5
S
'
/
• '
S
f y
^"3
^
s/
/ y*
/
7
•
' ?n
y
f /
f
^,
..-"-'
-^
"^
•
-
"1
5
_1.4
/ 1
l/
y/
A
/
/
>
^^?
• y
•J
? s
s
^v
• ^
''V
1?
IU
/l/i
'//
•
v""!
>
f •
22
^■v '
•^
//
*>
-7
r'\s'l
//
>^
li
/ // //
i' rs
*
ss
7/
-y
^5
/7Ur
S,*
1.3 /
if I 1
y
/s
i /
'/ L
*;si'.
''X,}
!«/R,
20 It
'A,
^A £r
h
s
-\
Wu
/ ('
•Y
i
If''
V
*
" 1
*Markof Schlumberger
© Schlumberger
1 2 3 4 5 6 7 8
"bit/firing
Purpose
This chart is used similarly to Chart Rt-10 to determine the correc-
tion applied to the log presentation of Rt and di determined from
geoVISION825 R r i n g, Rbit, and Rbd resistivity values.
< ►
Back to Contents
177
Formation Resistivity — LWD
geoVISION825* 8 1 /4-in. Resistivity-at-the-Bit Tool
Formation Resistivity and Diameter of Invasion — Open Hole
Schlumberger
Rt-17
Bit, Ring, and Deep Button Resistivity (8V4-in. tool) with ROP to Bit Face = 35 ft
20
10
9
8
7
6
Rbit/Rbd r
a
4
3
2
1
R,/Rxo = 50
d h = 12.25 in.
40
2.0
50
35
1 6 -r
S/
3.0
^ i
i /
• y
s. ,
ID
R t /R b it
J
s^
7 *
r •
V)'' iuu
3C
Si
s
.
• 1^
S4
• 70
9«
s
/
i
w 5C
1.3 _
**•
t>
*£
*~"? r
30
A
/
s
**/
i s
?fi
' i^
' s
s
' .,'■■*'
s
j/'
/ 4
/
* L
s
?
s
'/ySf
s
"^4*
*fi
*i
i
■>" i
^sfi
/,,
r b
ri t /n xo
/
* y
?4
A
V
i
X" •,
/'
i
' iy
i
"%/*
ls*s
' 10
1.2 j
/i
• /
s<>
Y S
'
St
r f
'j
/
/
' 7
>2 /
i/
sf
•
/
'5
's
li/l
?s*
* A
/
if
s
*
1 r i.
'/,
'
20 ill A/
r /
\
^U0Z'
//
1
J/S
1
*Markof Schlumberger
© Schlumberger
1 2 3 4 5 6 7 8 9 10 20
■'bit'r'ring
Purpose
This chart is used similarly to Chart Rt-10 to determine the correc-
tion applied to the log presentation of Rt and di determined from
geoVISION825 R r i n g, Rbit, and Rbd resistivity values.
178
< ►
Back to Contents
Formation Resistivity — LWD
arcVISION* Array Resistivity Compensated Tool— 400 kHz
Resistivity Anisotropy Versus Shale Volume — Open Hole
Schlumberger
Rt-31
(ohm-m)
Response Through Sand and Shale Layers at 90° Relative Dip
for R sh = 1 ohm-m and R sand = 5 ohm-m
10'
Phase-Shift Resistivity
10°
Ok^ "---^^
** ^^^^- ^^ * »»^.
■»» ^^^%»^ ^^^
0.2 0.4 0.6 0.8 1.0
Response Through Sand and Shale Layers at 90° Relative Dip
for R sh = 1 ohm-m and R sand = 20 ohm-m
10 2
R ps 10'
(ohm-m)
10°
Phase-Shift Resistivity
vv
0.2 0.4 0.6 0.8 1.0
R B d
(ohm-m)
10'
10°
Attenuation Resistivity
v>v
N^^^ — ~^^
"* ^^^^ — ^^^^
*Markof Schlumberger
© Schlumberger
Rad
(ohm-m)
0.2
0.4 0.6
V,„
0.8
1.0
10 2
10'
10°
Attenuation Resistivity
vv
s — '■
\ ^vj^ - — "^ - v^ —
s r 1 **^ ^*-^s^
0.2
0.4 0.6
0.8
1.0
Resistivity spacing
16 in.
22 in.
28 in.
34 in.
40 in.
Purpose
This chart illustrates the resistivity response, as affected by sand
and shale layers, of the arcVISION tool in horizontal wellbores.
The chart is used to determine the values of Rh and R v . These
corrections are already applied to the log presentation.
Description
The chart is constructed for shale layers at 90° relative dip to the
axis of the arcVISION tool. That is, both the layers of shale and the
tool are horizontal to the vertical. Other requirements for use of this
chart are that the shale resistivity (R S h) is 1 ohm-m and the sand
resistivity is 5 or 20 ohm-m.
Select the appropriate chart for the attenuation (R ar j) or phase-
shift (Rps) resistivity and values of resistivity of the shale (R S h) and
sand (Rsand)- Enter the chart with the volume of shale (V sn ) on the
x-axis and the resistivity on the y-axis. At the intersection point of
these two values move straight downward to the dashed blue curve
to read the value of Rh. Move upward to the solid green curve to read
the value of R v .
Chart Rt-32 is used to determine Rh and R v values for the 2-MHz
resistivity.
Back to Contents
179
Formation Resistivity — LWD
arcVISION* and ImPulse* Array Resistivity Compensated Tools — 2 MHz
Resistivity Anisotropy Versus Shale Volume — Open Hole
Schlumberger
Rt-32
Response Through Sand and Shale Layers at 90° Relative Dip
for R sh = 1 ohm-m and R sand = 5 ohm-m
10 2
PhasG-Shift Resistivity
Rp S 10'
ohm-m)
•*—
^ "■
^''^SSfe, """"•s^.
■*»
**
•* ^
"* - *. ^
10"
"* "* — ^
~~o^.
Response Through Sand and Shale Layers at 90° Relative Dip
10 2
Phase-Shift Resistivity
R ps
(ohm-m)
10 1
0.2 0.4 0.6 0.8 1.0
V.,
10°
v^^ :^s»— < =r — —
0.2 0.4 0.6 0.8 1.0
V h
10 2
Attenuation Resistivity
R„d 10'
(ohm-m)
10°
s ^^^ ^*'-»*»^
*. ^V> ^---.
N— ^Sw "''- » v w =
*i ^ ■■■ w^ — — \ —
** — ^*"^^ — — ^-"ii
*» ^^^. ^" m ^.
** — ^ ^ ^^^ — — >v —
*• — ^^^ s^- — — X. —
Rad
(ohm-m)
in 2
Attenuation Resistivity
m 1
— * — ~^^^
N.
*>»
^,
w°
~~~
---___
— — ^\
0.2 0.4 0.6 0.8
1.0
Resistivity spacing
16 in.
ft,
22 in.
R„
*Markof Schlumberger
© Schlumberger
Purpose
This chart is used similarly to Chart Rt-31 for arcVISION and
ImPulse 2-MHz resistivity. These corrections are already applied
to the log presentation.
28 in.
0.2 0.4 0.6 0.8 1.0
V.„
34 in.
40 in.
180
< ►
Back to Contents
Formation Resistivity — LWD
arcVISION* Array Resistivity Compensated Tool— 400 kHz
Resistivity Anisotropy Versus Dip — Open Hole
Schlumberger
Rt-33
10 3
Aniostropy Response for R h = 1 ohm-m and V(R V /RJ = 5
Phase-Shift Resistivity
(ohm-m)
in 2
10'
/-^
10°
10'
Aniostropy Response for R h = 1 ohm-m and V(R V /RJ = 2
Phase-Shift Resistivity
Rp S
(ohm-m)
10 20 30 40 50 60 70 80 90
Relative dip angle (°)
10°
10 20 30 40 50 60 70 80 90
Relative dip angle (°)
(ohm-m)
in 3
Attenuation Resistivity
in 2
10'
m°
R B d
(ohm-m)
10'
Attenuation Resistivity
m°
10 20 30 40 50 60 70 80 90
Relative dip angle (°)
10 20 30 40 50 60 70 80 90
Relative dip angle (°)
Resistivity spacing
16 in.
22 in.
28 in.
34 in.
40 in.
*Markof Schlumberger
© Schlumberger
Purpose
This chart is used to determine arcVISION R ps and R a d for relative
dip angles from to 90°. These corrections are already applied to
the log presentation.
Description
Enter the appropriate chart with the value of relative dip angle and
move to intersect the known resistivity spacing. Move horizontally
left to read R ps or R a d for the conditions of the horizontal resistivity
(Rh) = 1 ohm-m and the square root of the R v /Rh ratio.
< ►
Back to Contents
181
Formation Resistivity — LWD
arcVISION* and ImPulse* Array Resistivity Compensated Tools — 2 MHz
Resistivity Anisotropy Versus Dip — Open Hole
Schlumberger
Rt-34
10 3
Aniostropy Response for R h = 1 ohm-m and V(R„/RJ = 5
Phase-Shift Resistivity
(ohm-m)
m 2
III 1 S^
flsl
in'
m°
^0z
10'
Aniostropy Rosponse for R h = 1 ohm-m and V(R„/RJ = 2
Phase-Shift Resistivity
R PS
(ohm-m)
m°
.—- *
10 20 30 40 50 60 70 80 90
Relative dip angle (°)
10 20 30 40 50 60 70 80 90
Relative dip angle (°)
Rad
(ohm-m)
10 3
Attenua
ion Resistivi
ty
in 2
in 1
10°
Rad
(ohm-m)
10'
Attenuation Resistivity
1(1°
10 20 30 40 50 60 70 80 90
Relative dip angle (°)
10 20 30 40 50 60 70 80 90
Relative dip angle (°)
Resistivity spacing
16 in.
22 in.
28 in.
34 in.
40 in.
*Markof Schlumberger
© Schlumberger
Purpose
This chart is used similarly to Chart Rt-33 for arcVISION and
ImPulse 2-MHz resistivity. These corrections are already applied
to the log presentation.
182
< ►
Back to Contents
Formation Resistivity — LWD
arcVISION* Array Resistivity Compensated Tool— 400 kHz
Resistivity Anisotropy Versus Square Root of R v /Rh — Open Hole
Schlumberger
Rt-35
10 3
Aniostropy Response at 85° dip for R h = 1 ohm-m
Phase-Shift Resistivity
(ohm-m)
in 2
in 1
10°
10 1
Rps
(ohm-m)
Aniostropy Response at 65° dip for R h = 1 ohm-m
Phase-Shift Resistivity
10°
1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0
VfrvRj
1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0
VfRJPJ
(ohm-m)
in 3
Attenuation Resistivity
in 2
10 1
= '
in°
R B d
(ohm-m)
10'
Attenuation Resistivity
in°
1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0
V(R V /R h )
1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0
VfrvRT
Resistivity spacing
Ifiin
??in
?Rin
34 in
40 in
*Markof Schlumberger
© Schlumberger
Purpose
This chart and Chart Rt-36 reflect the effect of anisotropy on the
arcVISION resistivity response. These corrections are already
applied to the log presentation. As the square root of the R ¥ /Rh
ratio increases, the effect on the resistivity significantly increases.
Description
Enter the appropriate chart with the value of the phase-shift or
attenuation resistivity on the y-axis. Move horizontally to intersect
the resistivity spacing curve. At the intersection point read the value
of the square root of the R v /Rh ratio on the x-axis.
< ►
Back to Contents
183
Formation Resistivity — LWD
arcVISION* and ImPulse* Array Resistivity Compensated Tools — 2 MHz
Resistivity Anisotropy Versus Square Root of R v /Rh — Open Hole
Schlumberger
Rt-36
10 3
Aniostropy Response at 85° dip for R h = 1 ohm-m
Phase-Shift Resistivity
(ohm-m)
1fl 2
in'
m°
10 1
Aniostropy Rosponse at 65° dip for R h = 1 ohm-m
Phase-Shift Resistivity
Rp S
(ohm-m)
in°
1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0
1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0
VirvRJ
(ohm-m)
in 3
Attenuation Resistivity
in 2
in 1
.
m°
R B d
(ohm-m)
in>
Attenuation Resistivity
m°
1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0
1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0
VirvRT
VlRA
Resistivity spacing
Ifiin
??in
9Rin
34 in
40 in
*Markof Schlumberger
© Schlumberger
Purpose
This chart is used similarly to Chart Rt-35 for arcVISION and
ImPulse for 2-MHz resistivity. These corrections are already
applied to the log presentation.
184
< ►
Back to Contents
Formation Resistivity — LWD
arcVISION675* Array Resistivity Compensated Tool— 400 kHz
Conductive Invasion — Open Hole
Schlumberger
Rt-37
1
R xo and d; for R, ~ 10 ohm-m
16-in. R ps /40-in. R ad 01
0.01
ilH
Wt/'/I'l/Jlli
m¥ / 'i i /M\\
9S&^'''''/y/HI\l\
64>^y^|
WMf' 'A/M/j
60>
r*j7/jffmL
111
^r7rf-*0.8 Y W ,
^±j0.75/i// /
-5T~ Vmrllf/ /J
16
VLjfrY/
<0.65
5r \
0.3 ^o.t
^o'29- 55 l
<*
" y ■ ^ — — —
48
-"
44
40
Xi Ilw//
/ j
^Kl'/l
I /
/
U 2 °
dilin.P
32
' mill/
i
ill/ ' "
= 0.1 o
im
-m
28 '
r24
0.
*Markof Schlumberger
© Schlumberger
31 0.1 1.0
28-in. Rp S /40-in. R ad
Purpose
This log-log chart is used to determine the correction applied to
the log presentation of the 40-in. arcVISION675 resistivity measure-
ments, diameter of invasion (di), and resistivity of the flushed zone
(Rxo). These data are used to evaluate a formation for hydrocarbons.
Description
Enter the chart with the ratio of the 16-in. R ps /40-in. R a d on the y-axis
and 28-in. R ps /40-in. Radon the x-axis. The intersection point defines
the following:
■ di
■ Rxo
■ correction factor for 40-in. attenuation resistivity.
Chart Rt-38 is used for 2-MHz resistivity values. The corresponding
charts for resistive invasion are Charts Rt-39 and Rt-40.
Example
Given:
Find:
Answer:
16-in. R ps /40-in. R ad = 0.2 and 28-in. R ps /40-in. R ad = 0.4.
Rxo, di, and correction factor for 40-in. R a d-
At the intersection point of 0.2 on the y-axis and 0.4 on
the x-axis, di = 31.9 in., R xo = 1.1 ohm-m, and correction
factor = 0.955.
The value of the 40-in. R a d is reduced by the correction
factor: 40-in. R a d x 0.955.
Back to Contents
185
Formation Resistivity — LWD
Schlumberger
arcVISION675* and ImPulse* Array Resistivity Compensated Tools — 2 MHz
Conductive Invasion — Open Hole
Rt-38
R xo and d : for R t - 10 ohm-m
1.0
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f 2 WM
48,7
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/{' / A/ 1 1 £
7/40-in. R ad /R t =1
40-m. R ad
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28-in. R nq /40-in. R art
*Markof Schlumberger
© Schlumberger
Purpose
This chart is used similarly to Chart Rt-37 for arcVISION675 and
ImPulse 2-MHz resistivity. The corrections are already applied to
the log presentation.
186
< ►
Back to Contents
Formation Resistivity — LWD
arcVISION* Array Resistivity Compensated Tool— 400 kHz
Resistive Invasion — Open Hole
Schlumberger
Rt-39
FL and dfor R, ~10ohm-m
10
16-in. R ps /
40-in. R„ H
R xn = 300ohm-m
10
*Markof Schlumberger
© Schlumberger
28-in. R ps /40-in. R„
Purpose
This chart is used similarly to Chart Rt-37 to determine the correc-
tion applied to the arcVISION log presentation of di, R xo , and 40-in.
Rati for resistive invasion.
< ►
Back to Contents
187
Formation Resistivity — LWD
Schlumberger
arcVISION* and ImPulse* Array Resistivity Compensated Tools — 2 MHz
Resistive Invasion — Open Hole
Rt-40
R lo and d; for R, ~10ohm-m
2.4
2.2
2.0
16-in. R ps /
40-in. R„ ri
300ohm-m
*Markof Schlumberger
© Schlumberger
28-in. R ps /40-in. R ai
1.4
Purpose
This chart is used similarly to Chart Rt-39 to determine the correc-
tion applied to the arcVISION and ImPulse log presentation for
2-MHz resistivity.
< ►
Back to Contents
Formation Resistivity — LWD
arcVISION* Array Resistivity Compensated Tool— 400 kHz in Horizontal Well
Bed Proximity Effect — Open Hole
Schlumberger
Purpose
Charts Rt-41 and Rt-42 are used to calculate the correction applied
to the log presentation of Rt from the arcVISION tool at the
approach to a bed boundary. The value of Rt is used to calculate
water saturation.
Description
There are two sets of charts for differing conditions:
Example
Given:
Find:
Answer:
shoulder bed resistivity (Rshouider) = 10 ohm-m and Rt :
Rshouider = 10 ohm-m and Rt =100 ohm-m.
1 ohm-m
Rshouider = 10 ohm-m, Rt = 1 ohm-m, and
16-in. R ps = 1.5 ohm-m.
Bed proximity effect.
The top set of charts is appropriate for these resistivity
values. The ratio R ps /Rt = 1.5/1 = 1.5.
Enter the y-axis of the left-hand chart at 1.5 and move
horizontally to intersect the 16-in. curve. The corre-
sponding value on the x-axis is 1 ft, which is the distance
of the surrounding bed from the tool. At 2 ft from the
bed boundaiy, the value of 16-in. R ps = 1 ohm-m.
< ►
Back to Contents
continued on next page
189
Formation Resistivity — LWD
arcVISION* Array Resistivity Compensated Tool— 400 kHz in Horizontal Well
Bed Proximity Effect — Open Hole
Schlumberger
Rt-41
Rps/Rt
o
Bed Proximity Effect for Horizontal Well: R sh0U | der = lOohm-m and R,= 1 ohm-m
3
1
tt
k
1
^a*.
Rad/Rt
\1
?
1
n
01 23456789 10
Distanco to bod boundary (ft)
1 2 3 4 5 6 7 8 9 10
Distance to bed boundary (ft)
Rps/R«
Bed Proximity Effect for Horizontal Well: R sh0U | der = 10 ohm-m and R t = 100 ohm-m
3
?
1
n
Rad/Rt
?
1
n
1 2 3 4 5 6 7 8 9 10
Distance to bed boundary (ft)
1 2 3 4 5 6 7 8 9 10
Distance to bed boundary (ft)
Resistivity spacing
16 in.
22 in.
28 in.
34 in.
40 in.
*Markof Schlumberger
© Schlumberger
190
< ►
Back to Contents
Formation Resistivity — LWD
arcVISION* and ImPulse* Array Resistivity Compensated Tools — 2 MHz
in Horizontal Well
Bed Proximity Effect — Open Hole
Schlumberger
Rt-42
R ps /R t
Bed Proximity Effect for Horizontal Well: R sh0U | der = lOohm-m, Rt= 1 ohm-m
3
1
?
i\
1
n
1 2 3 4 5 6 7 8 9 10
Distance to bed boundary (ft)
Rad/Rt
?
1
n
12 3 4 5 6 7
Distance to bed boundary (ft)
10
Rps/Rt
Bed Proximity Effect for Horizontal Well: R shoU | dor = 10 ohm-m, R, = 100 ohm-m
3
?
[
1
I
^
^
stf*
^
^v
Rad/Rt
?
1
n
1 2 3 4 5 6 7 8 9 10
Distance to bed boundary (ft)
1 2 3 4 5 6 7 8 9 10
Distance to bed boundary (ft)
Resistivity spacing
16 in.
22 in.
28 in.
34 in.
40 in.
*Markof Schlumberger
© Schlumberger
Purpose
This chart is used similarly to Chart Rt-41 for arcVISION and
ImPulse 2-MHz resistivity. The correction is already applied
to the log presentation.
< ►
Back to Contents
191
Lithology — Wireline
Density and NGS* Natural Gamma Ray Spectrometry Tool
Mineral Identification — Open Hole
Schlumberger
Purpose Example
This chart is a method for identifying the type of clay in the wellbore. Given:
The values of the photoelectric factor (Pe) from the Litho-Density*
log and the concentration of potassium (K) from the NGS Natural
Gamma Ray Spectrometry tool are entered on the chart. p m( j.
Description Answer:
Enter the upper chart with the values of Pe and K to determine the
point of intersection. On the lower chart, plotting Pe and the ratio
of thorium and potassium (Th/K) provides a similar mineral evalua-
tion. The intersection points are not unique but are in general areas
defined by a range of values.
Environmentally corrected thorium concentration
(ThNGScorr) = 10.6 ppm, environmentally corrected
potassium concentration (KNGScorr) = 3.9%, and Pe = 3.2.
Mineral concentration of the logged clay.
The intersection points from plotting values of Pe and K
on the upper chart and Pe and Th/K ratio = 10.6/3.9 = 2.7
on the lower chart suggest that the clay mineral is illite.
192
Back to Contents
Lithology — Wireline
Density and NGS* Natural Gamma Ray Spectrometry Tool
Mineral Identification — Open Hole
Schlumberger
Lith-1
(former CP-18)
10
Photoelectric
factor, Pe
4 6
Potassium concentration, K (%)
Chlorite
=1
Glauconite
Biotite
O
i n
Montmorillonite
mite
O 1
Muscovite
ft 1
O
O 1 Kaolmite
10
10
Photoelectric
factor, Pe
0.1 0.2 0.3
*Markof Schlumberger
© Schlumberger
8
jlauconite
3iotite
1
Chlori
te
O
R
K
i
U
4
Mixe
d layer
I
lite
.
d
M
K
uscovit
1
e
1
V
<">
1 1
I
lontmorilk
nite
Kaolini
te
0.6 1 2 3 6 10
Thorium/potassium ratio, Th/K
20 30 60 100
< ►
Back to Contents
193
Lithology — Wireline
NGS* Natural Gamma Ray Spectrometry Tool
Mineral Identification — Open Hole
Schlumberger
Lith-2
(former CP-19)
Thorium
(ppm)
100% illite point .
Feldspar
Th/K = 0.3
Potassium evaporites, -30% feldspar
2 3
Potassium (%)
*Markof Schlumberger
© Schlumberger
Purpose
This chart is used to determine the type of minerals in a shale
formation from concentrations measured by the NGS Natural
Gamma Ray Spectrometry tool.
Description
Entering the chart with the values of thorium and potassium locates
the intersection point used to determine the type of radioactive min-
erals that compose the majority of the clay in the formation.
A sandstone reservoir with varying amounts of shaliness and
illite as the principal clay mineral usually plots in the illite segment
of the chart with Th/K between 2.0 and 3.5. Less shaly parts of the
reservoir plot closer to the origin, and shaly parts plot closer to the
70% illite area.
194
Back to Contents
Lithology — Wireline
Platform Express* Three-Detector Lithology Density Tool
Porosity and Lithology — Open Hole
Schlumberger
Purpose
This chart is used to determine the lithology and porosity of a forma-
tion. The porosity is used for the water saturation determination and
the lithology helps to determine the makeup of the logged formation.
Description
Note that this chart is designed for fresh water (fluid density
[Pf] = 1.0 g/cm 3 ) in the borehole. Chart Lith-4 is used for saltwater
(Pf = 1.1 g/cm 3 ) formations.
Values of photoelectric factor (Pe) and bulk density (Pb) from the
Platform Express Three-Detector Lithology Density (TLD) tool are
entered into the chart. At the point of intersection, porosity and
lithology values can be determined.
Example
Given:
Find:
Answer:
Freshwater drilling mud, Pe = 3.0, and bulk density :
2.73 g/cm 3 .
Freshwater drilling mud, Pe = 1.6, and bulk density :
2.24 g/cm 3 .
Porosity and lithology.
For the first set of conditions, the formation is a
dolomite with 8% porosity.
The second set is for a quartz sandstone formation
with 30% porosity.
< ►
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continued on next page
195
Lithology — Wireline
Platform Express* Three-Detector Lithology Density Tool
Porosity and Lithology — Open Hole
Schlumberger
Lith-3
(former CP-16)
Fresh Water (p f = 1.0g/cm 3 ), Liquid-Filled Borehole
1.9
Bulk density, p h
(g/cm 3 )
v
-V
V
\
1 G
J
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ji_J
05^
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2 3 4
Photoelectric factor, Pe
*Markof Schlumberger
© Schlumberger
196
< ►
Back to Contents
Lithology — Wireline
Platform Express* Three-Detector Lithology Density Tool
Porosity and Lithology — Open Hole
Schlumberger
Lith-4
(former CP-17)
Salt Water (p f = 1.1 g/cm 3 ), Liquid-Filled Borehole
1.9
Bulk density, p b
(g/cm 3 )
■ ■
\
■ ■
•V
<MI
1
♦i '
T
CO
CO
, ■
v
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4
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*Markof Schlumberger
© Schlumberger
3 4
Photoelectric factor, Pe
This chart is used similarly to Chart Lith-3 for lithology and poros- bulk density (pb) from the Platform Express TLD tool in saltwater
ity determination with values of photoelectric factor (Pe) and borehole fluid.
< ►
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197
Lithology — Wireline, LWD
Density Tool
Apparent Matrix Volumetric Photoelectric Factor — Open Hole
Schlumberger
Lith-5
(former CP-20)
3.0
2.5
2.0
Bulk density, p b
(g/cm 3 )
_ . . . ,oiio nr,n
10
20
30
4q Apparent total
porosity, cp ta (%)
-resn waier (u ppmi, p f = i.u g/cm°, u f = u.jao
5alt>A/atDr /9nnnnn nnml n. - 1 11 n/rm3 II. - 1 ^R
'
^,7 .
7
//
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6
© Schlumberger
5 4 3 2 1 4 6 8 10 12 14
Photoelectric factor, Pe Apparent matrix
volumetric photoelectric factor, U maa
Purpose
This chart is used to determine the apparent matrix volumetric
photoelectric factor (U ma a) for the Chart Lith-6 percent lithology
determination.
Description
This chart is entered with the values of bulk density (pb) and Pe from
a density log. The value of the apparent total porosity (cpta) must also
be known. The appropriate solid lines on the right-hand side of the
chart that indicate a freshwater borehole fluid or dotted lines that
represent saltwater borehole fluid are used depending on the salinity
of the borehole fluid. Uf is the fluid photoelectric factor.
Example
Given:
Find:
Answer:
Pe = 4.0, pb = 2.5 g/cm 3 , <|)ta = 25%, and freshwater
borehole fluid.
Apparent matrix volumetric photoelectric factor (U ma a).
Enter the chart with the Pe value (4.0) on the left-hand
x-axis, and move upward to intersect the curve for
pb = 2.5 g/cm 3 .
From that intersection point, move horizontally right to
intersect the <|)ta value of 25%, using the blue freshwater
curve.
Move vertically downward to determine the U maa value
on the right-hand x-axis scale: U ma a = 13.
198
Back to Contents
Lithology — Wireline, LWD
Density Tool
Lithology Identification — Open Hole
Schlumberger
Purpose Example
This chart is used to identify the rock mineralogy through comparison Given:
of the apparent matrix grain density (pmaa) and apparent matrix volu-
metric photoelectric factor (U ma a). Find:
Description Answer:
The values of p maa and U ma a are entered on the y- and x-axis, respec-
tively. The rock mineralogy is identified by the proximity of the point
of intersection of the two values to the labeled points on the plot.
The effect of gas, salt, etc., is to shift data points in the directions
shown by the arrows.
pmaa
Umaa
2.74 g/cm 3 (from Chart Lith-9 or Lith-10) and
13 (from Chart Lith-5).
Matrix composition of the formation.
Enter the chart with pmaa = 2.74 g/cm 3 on the y-axis and
Umaa = 13 on the x-axis. The intersection point indicates
a matrix mixture of 20% dolomite and 80% calcite.
< ►
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continued on next page
199
Lithology — Wireline, LWD
Density Tool
Lithology Identification — Open Hole
Schlumberger
Lith-6
(former CP-21)
T>
A
' '
2.3 ::
Sa
t
., k
2.4 1 _.
\ o
X ^"
1 £
k- =S
V ^,
^ ~S~
i < - j
?.R r
2.6 K-feldspar
j\
O:
'ire
— _^ i
n In/rm 11 V "~ >V -^._ 40
-i-»-
PmaaW UM / \ S \ ?f^—
60 "
— >1v"- 80
27 = 5? -5s^ \
^ > *yt.... >, ^
\ S \ ~~tx Calcite
s, v j^ ?^-S
^c— — ^\/_l
*J ' '•jS^ V -S^S
* \j 1 .y'x ""** —
^UkJy'i i i\ 1 L/f "W 5
' - \J "' \.
> v -XLt
0, \ >tj > ^' V
2.8 _l8>, X-F^Sr £S-
"}> V-I- V »<v
-+*• V \ s ^
^ ^ &r^ <s$?4-
S r ^ X^ v^°
5^~
-V^ * 7 ^°V
J?<Si * »\«
S 1 t ly
~LJ
n i ■+
j 9 uoiomite
^^
^k
.... f.
Anhydrite L^
3.0
■ i- r»
llhte ^u 1-
3.1
2 4 6 8
Apparent matrix volumetri
© Schlumberger
10 12 14 16
: photoelectric factor, U maa
200
< ►
Back to Contents
Lithology — Wireline, LWD
Environmentally Corrected Neutron Curves
M-N Plot for Mineral Identification— Open Hole
Schlumberger
Purpose
This chart is used to help identify mineral mixtures from sonic,
density, and neutron logs.
Description
Because M and N slope values are practically independent of porosity
except in gas zones, the porosity values they indicate can be corre-
lated with the mineralogy. (See Appendix E for the formulas to calcu-
late M and N from sonic, density, and neutron logs.)
Enter the chart with M on the y-axis and N on the x-axis. The
intersection point indicates the makeup of the formation. Points for
binary mixtures plot along a line connecting the two mineral points.
Ternary mixtures plot within the triangle defined by the three con-
stituent minerals. The effect of gas, shaliness, secondary porosity,
etc., is to shift data points in the directions shown by the arrows.
The lines on the chart are divided into numbered groups by poros-
ity range as follows:
1. tj> = (tight formation)
2. <j) = to 12 p.u.
3. <> = 12 to 27 p.u.
4. c> = 27 to 40 p.u.
Example
Given: M = 0.79 and N = 0.51.
Find: Mineral composition of the formation.
Answer: The intersection of the M and N values indicates dolomite
in group 2, which has a porosity between to 12 p.u.
< ►
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201
Lithology — Wireline, LWD
Environmentally Corrected Neutron Curves
M-N Plot for Mineral Identification— Open Hole
Schlumberger
Lith-7
(former CP-8)
© Schlumberger
1.1
c
1.0
0.9
0.8
M
0.7
0.6
0.5
oFreshwater mud
p ( = 1.0Mg/m 3 ,t, = 620|as/m
I
»
/
P
■
, = 1.0g/cm 3 ,t,= 189u.s/ft
/ Gypsum
Saltwater mud
p, = 1.1 Mg/m 3 ,t, = 607ns/m
p f = 1.1 g/cm 3 ,t f =185u.s/ft
t
t
^
•*
1 1
Secondar\
porosity
r
*/-
•
1
1
v ma = 5943 m/s
j
• J»
= 1 9,500 ft/s
lim
3StO
ne)
•
•
Q
*•-
•*
uartz sandstone
= 5486 m/s
M
>W
»
XT
4
= 18,000 ft/s
Dolomite ^
r
r
324
1
j
•
AnhydritG
/
/
/
V
'
r"
Sulfur
Af
proxim
ate
shale
region
0.
3 0.4 0.5 0.6 0.7
N
8
202
< ►
Back to Contents
Lithology — Wireline
Environmentally Corrected APS* Curves
M-N Plot for Mineral Identification— Open Hole
Schlumberger
Purpose
This chart is used to help identify mineral mixtures from APS
Accelerator Porosity Sonde neutron logs.
Description
Because M and N values are practically independent of porosity
except in gas zones, the porosity values they indicate can be corre-
lated with the mineralogy. (See Appendix E for the formulas to cal-
culate M and N from sonic, density, and neutron logs.)
Enter the chart with M on the y-axis and N on the x-axis. The
intersection point indicates the makeup of the formation. Points for
binary mixtures plot along a line connecting the two mineral points.
Ternary mixtures plot within the triangle defined by the three con-
stituent minerals. The effect of gas, shaliness, secondary porosity,
etc., is to shift data points in the directions shown by the arrows.
The lines on the chart are divided into numbered groups by poros-
ity range as follows:
1. tj> = (tight formation)
2. <j) = to 12 p.u.
3. <> = 12 to 27 p.u.
4. c> = 27 to 40 p.u.
Because the dolomite spread is negligible, a single dolomite point
is plotted for each mud.
Example
Given: M = 0.80 and N = 0.55.
Find: Mineral composition of the formation.
Answer: Dolomite.
< ►
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continued on next page
203
Lithology — Wireline
Environmentally Corrected APS* Curves
M-N Plot for Mineral Identification— Open Hole
Schlumberger
Lith-8
(former CP-8a)
1.1
M
o Freshwater muc
i
»
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204
< ►
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Lithology — Wireline, LWD
Bulk Density or Interval Transit Time and Apparent Total Porosity
Apparent Matrix Parameters — Open Hole
Schlumberger
Purpose
Charts Lith-9 (customary units) and Lith-10 (metric units) provide
values of the apparent matrix internal transit time (t maa ) and appar-
ent matrix grain density (pmaa) for the matrix identification (MID)
Charts Lith-11 and Lith-12. With these parameters the identification
of rock mineralogy or lithology through a comparison of neutron,
density, and sonic measurements is possible.
Description
Determining the values of t ma a and p maa to use in the MID Charts
Lith-11 and Lith-12 requires three steps.
First, apparent crossplot porosity is determined using the appro-
priate neutron-density and neutron-sonic crossplot charts in the
"Porosity" section of this book. For data that plot above the sand-
stone curve on the charts, the apparent crossplot porosity is denned
by a vertical projection to the sandstone curve.
Second, enter Chart Lith-9 or Lith-10 with the interval transit
time (t) to intersect the previously determined apparent crossplot
porosity. This point defines t maa .
Third, enter Chart Lith-9 or Lith-10 with the bulk density (Pb)
to again intersect the apparent crossplot porosity and define p maa .
The values determined from Charts Lith-9 and Lith-10 for t maa and
pm aa are cross plotted on the appropriate MID plot (Charts Lith-11
and Lith-12) to identify the rock mineralogy by its proximity to the
labeled points on the plot.
Example
Given:
Find:
Answer:
Apparent crossplot porosity from density-neutron = 20%,
Pb = 2.4 g/cm 3 , apparent crossplot porosity from
neutron-sonic = 30%, and t = 82 \is/ft.
pm aa and tm aa .
pnm = 2.75 g/cm 3 and t maa =
46(is/ft.
< ►
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continued on next page
205
Lithology — Wireline, LWD
Bulk Density or Interval Transit Time and Apparent Total Porosity
Apparent Matrix Parameters — Open Hole
Schlumberger
Lith-9
(customary, former CP-14)
Fluid Density = 1.0 g/cm 3
Apparent matrix transit time, t maa (u.s/ft)
?n 130 120 110 100 90 80 70 60 50 40 30 nf)
2.9
2.8
2.7
2.6
Bulk density, 2 5
p„(g/cm 3 )
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Apparent matrix density, p maa (g/cm 3 )
]
206
< ►
Back to Contents
Lithology — Wireline, LWD
Bulk Density or Interval Transit Time and Apparent Total Porosity
Apparent Matrix Parameters — Open Hole
Schlumberger
Lith-10
(metric, former CP-14m)
Fluid Density = 1.0 g/cm 3
Apparent matrix transit time, t maa (u.s/m)
?n 350 325 300 275 250 225 200 175 150 125 1 00 qRn
2.9
2.8
2.7
2.6
Bulk density, 2.5
p„(g/cm 3 )
2.4
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2.9 2.8 2.7 2.6 2.5 2.4 2.3 2.2 2.1 2.
Apparent matrix density, p maa (g/cm 3 )
Purpose
Charts Lith-9 (customary units) and Lith-10 (metric units) provide
values of the apparent matrix internal transit time (t ma a) and appar-
ent matrix grain density (pmaa) for the matrix identification (MID)
Charts Lith-11 and Lith-12. With these parameters the identification
of rock mineralogy or lithology through a comparison of neutron,
density, and sonic measurements is possible.
< ►
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207
Lithology — Wireline, LWD
Density Tool
Matrix Identification (MID)— Open Hole
Schlumberger
Purpose
Charts Lith-11 and Lith-12 are used to establish the type of mineral
predominant in the formation.
Description
Enter the appropriate (customaiy or metric units) chart with
the values established from Charts Lith-9 or Lith-10 to identify the
predominant mineral in the formation. Salt points are defined for
two tools, the sidewall neutron porosity (SNP) and the CNL*
Compensated Neutron Log. The presence of secondary porosity
in the form of vugs or fractures displaces the data points parallel
to the apparent matrix internal transit time (t maa ) axis. The presence
of gas displaces points to the right on the chart. Plotting some shale
points to establish the shale trend lines helps in the identification
of shaliness. For fluid density (pf) other than 1.0 g/cm 3 use the table
to determine the multiplier to correct the apparent total density
porosity before entering Chart Lith-11 or Lith-12.
pf
Multiplier
1.00
1.00
1.05
0.98
1.10
0.95
1.15
0.93
Example
Given:
Find:
Answer:
pmaa = 2.75 g/cm 3 , t maa = 56 us/ft (from Chart Lith-9),
and pf = 1.0 g/cm 3 .
The predominant mineral.
The formation consists of both dolomite and calcite,
which indicates a dolomitized limestone. The formation
used in this example is from northwest Florida in the
Jay field. The vugs (secondary porosity) created by the
dolomitization process displace the data point parallel
to the dolomite and calcite points.
208
Back to Contents
Lithology — Wireline, LWD
Density Tool
Matrix Identification (MID)— Open Hole
Schlumberger
Lith-11
(customary, former CP-15)
20
2.1
2.2
2.3
2.4
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30 40 50 60 70
tmaa (^S/ft)
^ ►
Back to Contents
209
Lithology — Wireline, LWD
Density Tool
Matrix Identification (MID)— Open Hole
Schlumberger
Lith-12
(metric, former CP-15m)
Salt L.
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Purpose
Chart Lith-12 is used similarly to Chart Lith-11 to establish the mineral
type of the formation.
210
< ►
Back to Contents
Porosity — Wireline, LWD
Sonic Tool
Porosity Evaluation-
-Open Hole
Schlumberger
Purpose
This chart is used to convert sonic log slowness time (At) values
into those for porosity (c|)).
Description
There are two sets of curves on the chart. The blue set for matrix
velocity (v ma ) employs a weighted-average transform. The red set
is based on the empirical observation of lithology (see Reference
20). For both, the saturating fluid is assumed to be water with
a velocity (v f ) of 5,300 ft/s (1,615 m/s).
Enter the chart with the slowness time from the sonic log on the
x-axis. Move vertically to intersect the appropriate matrix velocity
or lithology curve and read the porosity value on the y-axis. For rock
mixtures such as limy sandstones or cherty dolomites, intermediate
matrix lines may be interpolated.
To use the weighted-average transform for an unconsolidated sand,
a lack-of-compaction correction (B cp ) must be made. Enter the chart
with the slowness time and intersect the appropriate compaction
correction line to read the porosity on the y-axis. If the compaction
correction is not known, it can be determined by working backward
from a nearby clean water sand for which the porosity is known.
Example: Consolidated Formation
Given: At = 76 \xs/ft in a consolidated formation with
V ma = 18,000 ft/S.
Find: Porosity and the formation lithology (sandstone,
dolomite, or limestone).
Answer: 15% porosity and consolidated sandstone.
Example: Unconsolidated Formation
Given: Unconsolidated formation with At = 100 (is/ft in
a nearby water sand with a porosity of 28%.
Find: Porosity of the formation for At = 110 (is/ft.
Answer: Enter the chart with 100 \is/ft on the x-axis and move
vertically upward to intersect 28-p.u. porosity. This
intersection point indicates the correction factor curve
of 1.2. Use the 1.2 correction value to And the porosity for
the other slowness time. The porosity of an unconsoli-
dated formation with At = 110 us/ft is 34 p.u.
Lithology
Vma (ft/S)
At ma (us/ft)
Vma (m/s)
At ma (|is/m)
Sandstone
18,000-19,500
55.5-51.3
5,486-5,944
182-168
Limestone
21,000-23,000
47.6-43.5
6,400-7,010
156-143
Dolomite
23,000-26,000
43.5-38.5
7,010-7,925
143-126
< ►
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continued on next page
211
Porosity — Wireline, LWD
Sonic Tool
Porosity Evaluation — Open Hole
Schlumberger
Por-1
(customary, former Por-3)
50
v, = 5,300 ft/s
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40 50 60 70 80 90 100 110 120 13
1 nterval transit time. At (|is/ft)
212
< ►
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Porosity — Wireline, LWD
Sonic Tool
Porosity Evaluation — Open Hole
Schlumberger
Por-2
(metric, former Por-3m)
50
v f = 1,615 m/s
50
40
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Porosity,
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Purpose
This chart is used similarly to Chart Por-1 with metric units.
< ►
Back to Contents
213
Porosity — Wireline, LWD
Density Tool
Porosity Determination — Open Hole
Schlumberger
Por-3
(former Por-5)
P,(g/cm 3
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2.8 2.6 2.4 2.2 !
, 2.31
Bulk density, p b (g/cm )
.0
Purpose
This chart is used to convert grain density (g/cm 3 ) to density porosity.
Description
Values of log-derived bulk density (pb) corrected for borehole size,
matrix density of the formation (pma), and fluid density (pf) are used
to determine the density porosity ((|)d) of the logged formation. The
pf is the density of the fluid saturating the rock immediately sur-
rounding the borehole — usually mud filtrate.
Enter the borehole-corrected value of pb on the x-axis and move
vertically to intersect the appropriate matrix density curve. From the
intersection point move horizontally to the fluid density line. Follow
the porosity trend line to the porosity scale to read the formation
porosity as determined by the density tool. This porosity in combina-
tion with CNL* Compensated Neutron Log, sonic, or both values of
porosity can help determine the rock type of the formation.
Example
Given:
Find:
Answer:
pb = 2.31 g/cm 3 (log reading corrected for borehole
effect), p ma = 2.71 g/cm 3 (calcite mineral), and
pt = 1.1 g/cm 3 (salt mud).
Density porosity.
(|)d = 25 p.u.
214
Back to Contents
Porosity — Wireline
Schlumberger
APS* Near-to-Array (APLC) and Near-to-Far (FPLC) Logs
Epithermal Neutron Porosity Equivalence — Open Hole
Purpose
This chart is used for the apparent limestone porosity recorded by the
APS Accelerator Porosity Sonde or sidewall neutron porosity (SNP)
tool to provide the equivalent porosity in sandstone or dolomite for-
mations. It can also be used to obtain the apparent limestone poros-
ity (used for the various crossplot porosity charts) for a log recorded
in sandstone or dolomite porosity units.
Description
Enter the x-axis with the corrected near-to-array apparent limestone
porosity (APLC) or near-to-far apparent limestone porosity (FPLC)
and move vertically to the appropriate lithology curve. Then read the
equivalent porosity on the y-axis. For APS porosity recorded in sand-
stone or dolomite porosity units enter that value on the y-axis and
move horizontally to the recorded lithology curve. Then read the
apparent limestone neutron porosity for that point on the x-axis.
The APLC is the epithermal short-spacing apparent limestone
neutron porosity from the near-to-array detectors. The log is auto-
matically corrected for standoff during acquisition. Because it is
epithermal this measurement does not need environmental correc-
tions for temperature or chlorine effect. However, corrections for
mud weight and actual borehole size should be applied (see Chart
Neu-10). The short spacing means that the effect of density and
therefore the lithology on this curve is minimal.
The FPLC is the epithermal long-spacing apparent limestone neu-
tron porosity acquired from the near-to-far detectors. Because it is
epithermal this measurement does not need environmental correc-
tions for temperature or chlorine effect. However, corrections for
mud weight and actual borehole size should be applied (see Chart
Neu-10). The long spacing means that the density and therefore
lithology effect on this curve is pronounced, as seen on Charts Por-13
and Por-14.
The HPLC curve is the high- resolution version of the APLC curve.
The same corrections apply.
Resolution
Short Spacing
Long Spacing
Normal
APLC
Epithermal neutron porosity ( E N P 1 ) t
FPLC
Enhanced
HPLC
HNPI f
HFLC
T Not formation-salinity corrected.
Example: Equivalent Porosity
Given: APLC = 25 p.u. and FPLC = 25 p.u.
Find: Porosity for sandstone and for dolomite.
Answer: Sandstone porosity from APLC = 28.5 p.u. and sandstone
porosity from FPLC = 30 p.u.
Dolomite porosity = 24 and 20 p.u., respectively.
Example: Apparent Porosity
Given: Clean sandstone porosity = 20 p.u.
Find: Apparent limestone neutron porosity.
Answer: Enter the y-axis at 20 p.u. and move horizontally to
the quartz sandstone matrix curves. Move vertically
from the points of intersection to the x-axis and read
the apparent limestone neutron porosity values.
APLC = 16.8 p.u. and FPLC = 14.5 p.u.
< ►
Back to Contents
continued on next page
215
Porosity — Wireline
APS* Near-to-Array (APLC) and Near-to-Far (FPLC) Logs
Epithermal Neutron Porosity Equivalence — Open Hole
Schlumberger
Por-4
(former Por-13a)
40
30
True porosity
for indicated 20
matrix material,
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10
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FPLC
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10 20 30 40
Apparent limestone neutron porosity, ^ SNPl . 01 .(p,u.)
Apparent limestone neutron porosity, cj> A p St . or (p.u.)
216
< ►
Back to Contents
Porosity — Wireline
Thermal Neutron Tool
Porosity Equivalence — Open Hole
Schlumberger
Por-5
(former Por-13b)
40
30
True porosity
for indicated 20
matrix material,
<Kp.u.)
10
Formation salinity
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10 20 30 40
Apparent limestone neutron porosity, <4> CNLcor (p.u.)
Purpose
This chart is used to convert CNL* Compensated Neutron Log porosity
curves (TNPH or NPHI) from one lithology to another. It can also be
used to obtain the apparent limestone porosity (used for the various
crossplot porosity charts) from a log recorded in sandstone or dolomite
porosity units.
Description
To determine the porosity of either quartz sandstone or dolomite
enter the chart with the either the TNPH or NPHI corrected
apparent limestone neutron porosity (<|>cNLcor) on the x-axis. Move
vertically to intersect the appropriate curve and read the porosity
for quartz sandstone or dolomite on the y-axis. The chart has a
built-in salinity correction for TNPH values.
NPHI Thermal neutron porosity (ratio method)
NPOR Neutron porosity (environmentally corrected and
enhanced vertical resolution processed)
TNPH Thermal neutron porosity (environmentally corrected)
Example
Given:
Find:
Answer:
Quartz sandstone formation, TNPH = 18 p.u. (apparent
limestone neutron porosity), and formation salinity =
250,000 ppm.
Porosity in sandstone.
From the TNPH porosity reading of 18 p.u. on the x-axis,
project a vertical line to intersect the quartz sandstone
dashed red curve. From the y-axis, the porosity of the
sandstone is 24 p.u.
Back to Contents
217
Porosity — Wireline
Thermal Neutron Tool— CNT-D and CNT-S 2 1 /2-in. Tools
Porosity Equivalence — Open Hole
Schlumberger
Por-6
True porosity
for indicated
matrix material,
tt> (p.u.)
© Schlumberger
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Apparent limestone neutron porosity (p.u.)
Purpose
This chart is used similarly to Chart Por-5 to convert 2!/2-in. compen-
sated neutron tool (CNT) porosity values (TNPH) from one lithology
to another. Fresh formation water is assumed.
218
< ►
Back to Contents
Porosity— LWD
adnVISI0N475* 4.75-in. Azimuthal Density Neutron Tool
Porosity Equivalence — Open Hole
Schlumberger
Por-7
40
35
30
25
True porosity
for indicated 20
matrix material,
<|>(p.u.)
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10
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5 5 10 15 20 25 30 35 40
Corrected apparent limestone neutron porosity, (]> A oNcor (P u -)
Purpose
This chart is used to determine the porosity of sandstone, limestone,
or dolomite from the corrected apparent limestone porosity measured
with the adnVISION475 4.75-in. tool.
Description
Enter the chart on the x-axis with the corrected apparent limestone
porosity from Chart Neu-31 to intersect the curve for the appropriate
formation material. Read the porosity on the y-axis.
< ►
Back to Contents
219
Porosity— LWD
Schlumberger
adnVISION675* 6.75-in. Azimuthal Density Neutron Tool
Porosity Equivalence — Open Hole
Por-8
40
35
30
25
Truo porosity
for indicated 20
matrix material,
<t>(p.u.)
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5 5 10 15 20 25 30 35 40
Corrected apparent limestone neutron porosity, <t> A DN.;or (P u -)
Purpose
Chart Por-8 is used similarly to Chart Por-7 for determining
porosity from the corrected apparent limestone porosity from
the adnVISION675 6.75-in. tool.
220
< ►
Back to Contents
Porosity— LWD
Schlumberger
adnVISION825* 8.25-in. Azimuthal Density Neutron Tool
Porosity Equivalence — Open Hole
Por-9
40
35
30
25
True porosity
(p.u.) 20
15
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© Schlumberger
5 5 10 15 20 25 30 35 40
Corrected apparent limestone neutron porosity, (t>ADN Cor (P- u -)
Purpose
Chart Por-9 is used similarly to Chart Por-7 for determining
porosity from the corrected apparent limestone porosity from
the adnVISION825 8.25-in. tool.
< ►
Back to Contents
221
Porosity— LWD
Schlumberger
EcoScope* 6.75-in. Integrated LWD Tool, BPHI Porosity
Porosity Equivalence — Open Hole
Por-10
40
35
30
25
True porosity
for indicated 20
matrix material,
<j>(P-U.)
15
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5 5 10 15 20 25 30 35 40
Corrected apparent limestone BPHI porosity (p.u.)
Purpose
This chart is used to determine the porosity of sandstone, limestone,
or dolomite from the corrected apparent limestone BPHI porosity
measured with the EcoScope 6.75-in. LWD tool.
Use this chart only with EcoScope best thermal neutron porosity
(BPHI) measurements; use Chart Por- 10a with EcoScope thermal
neutron porosity (TNPH) measurements.
Description
Enter the chart on the x-axis with the corrected apparent limestone
BPHI porosity from Chart Neu-43 or Neu-44 to intersect the curve for
the appropriate formation material. Read the porosity on the y-axis.
222
< ►
Back to Contents
Porosity— LWD
EcoScope* 6.75-in. Integrated LWD Tool, TNPH Porosity
Porosity Equivalence — Open Hole
Schlumberger
Por-10a
40
35
30
25
True porosity
for indicated 20
matrix material,
<Kp-u.)
15
10
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© Schlumberger
5 5 10 15 20 25 30 35 40
Corrected apparent limestone TNPH porosity (p.u.)
Purpose
This chart is used to determine the porosity of sandstone, limestone,
or dolomite from the corrected apparent limestone TNPH porosity
measured with the EcoScope 6.75-in. LWD tool.
Use this chart only with EcoScope thermal neutron porosity
(TNPH) measurements; use Chart Por-10 with EcoScope best
thermal neutron porosity, average (BPHI) measurements.
Description
Enter the chart on the x-axis with the corrected apparent limestone
TNPH porosity from Chart Neu-45 or Neu-46 to intersect the curve for
the appropriate formation material. Read the porosity on the y-axis.
< ►
Back to Contents
223
Porosity — Wireline
CNL* Compensated Neutron Log and Litho-Density 4
(fresh water in invaded zone)
Porosity and Lithology — Open Hole
Schlumberger
Tool
Purpose
This chart is used with the bulk density and apparent limestone
porosity from the CNL Compensated Neutron Log and Litho-Density
tools, respectively, to approximate the lithology and determine the
crossplot porosity.
Description
Enter the chart with the environmentally corrected apparent neu-
tron limestone porosity on the x-axis and bulk density on the y-axis.
The intersection of the two values describes the crossplot porosity
and lithology.
If the point is on a lithology curve, that indicates that the forma-
tion is primarily that lithology. If the point is between the lithology
curves, then the formation is a mixture of those lithologies. The posi-
tion of the point in relation to the two lithology curves as composi-
tion endpoints indicates the mineral percentages of the formation.
The porosity for a point between lithology curves is determined
by scaling the crossplot porosity by connecting similar numbers on
the two lithology curves (e.g., 20 on the quartz sandstone curve to
20 on the limestone curve). The scale line closest to the point repre-
sents the crossplot porosity.
Chart Por-12 is used for the same purpose as this chart for salt-
water-invaded zones.
Example
Given:
Find:
Answer:
Corrected apparent neutron limestone porosity =
16.5 p.u. and bulk density = 2.38 g/cm 3 .
Crossplot porosity and lithology.
Crossplot porosity = 18 p.u. The lithology is approxi-
mately 40% quartz and 60% limestone.
224
< ►
Back to Contents
Porosity — Wireline
CNL* Compensated Neutron Log and Litho-Density*Tool
(fresh water in invaded zone)
Porosity and Lithology — Open Hole
Schlumberger
Por-11
(former CP-1e)
1.9
Liquid-Filled Borehole (p, = 1.000 g/cm 3 and C f = ppm)
2.0
2.1
2.2
2.3
2.4
Bulk
density,
p„(g/cm 3 ) 2 - 5
2.6
2.7
2.8
2.9
3.0
&
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40
35
30
25
20
Density
15 porosity,
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(p ma = 2.71 g/cm 3 ,
10 p, = 1.0 g/cm 3 )
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10 20 30 40
Corrected apparent limestone neutron porosity, <|) CNLcor (p.u.)
< ►
Back to Contents
225
Porosity — Wireline
CNL* Compensated Neutron Log and Litho-Density*Tool
(saltwater in invaded zone)
Porosity and Lithology — Open Hole
Schlumberger
Por-12
(former CP-11)
1.9
Liquid-filled borehole (p, = 1.190 g/cm 3 and C, = 250,000 ppm)
2.0
2.1
2.2
2.3
2.4
Bulk
density,
p b (g/cm 3 ) 2 - 5
2.6
2.7
2.8
2.9
3.0
45
40
35
30
25
20 Density
porosity,
<t>D (P-U.)
15 ( Pma = 2.71 g/cm 3 ,
p f = 1.19 g/cm 3 )
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10 20 30 40
Corrected apparent limestone neutron porosity, <t>cNLcor(P- u -)
Purpose
This chart is used similarly to Chart Por-11 with CNL Compensated
Neutron Log and Litho-Density values to approximate the lithology
and determine the crossplot porosity in the saltwater-invaded zone.
Example
Given:
Find:
Answer:
Corrected apparent neutron limestone porosity =
16.5 p.u. and bulk density = 2.38 g/cm 3 .
Crossplot porosity and lithology.
Crossplot porosity = 20 p.u. The lithology is approxi-
mately 55% quartz and 45% limestone.
226
< ►
Back to Contents
Porosity — Wireline
APS* and Litho-Density* Tools
Porosity and Lithology — Open Hole
Schlumberger
Por-13
(former CP-1g)
1.9
Liquid-Filled Borehole (p f = 1.000 g/cm 3 and C f = ppm)
2.0
2.1
2.2
2.3
2.4
Bulk density,
p b (g/cm 3 ) 25
2.6
2.7
2.8
2.9
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10 20 30 40
Corrected APS apparent limestone neutron porosity, <t> APS ,, or (p.u.)
Purpose
This chart is used to determine the lithology and porosity from the
Litho-Density bulk density and APS Accelerator Porosity Sonde porosity
log curves (APLC or FPLC). This chart applies to boreholes filled
with freshwater drilling fluid; Chart Por-14 is used for saltwater fluids.
Description
Enter either the APLC or FPLC porosity on the x-axis and the bulk
density on the y-axis. Use the blue matrix curves for APLC porosity
values and the red curves for FPLC porosity values. Anhydrite plots
on separate curves. The gas correction direction is indicated for for-
mations containing gas. Move parallel to the blue correction line if
the APLC porosity is used or to the red correction line if the FPLC
porosity is used.
Example
Given:
Find:
Answer:
APLC porosity = 8 p.u. and bulk density = 2.2 g/cm 3 .
Approximate quartz sandstone porosity.
Enter at 8 p.u. on the x-axis and 2.2 g/cm 3 on the y-axis
to find the intersection point is in the gas-in-formation
correction region. Because the APLC porosity value was
used, move parallel to the blue gas correction line until
the blue quartz sandstone curve is intersected at approx-
imately 19 p.u.
Back to Contents
227
Porosity — Wireline
APS* and Litho-Density* Tools (saltwater formation)
Porosity and Lithology — Open Hole
Schlumberger
Por-14
(former CP-1h)
1.9
Liquid-Filled Borehole (p, = 1.190 g/cm 3 and C, = 250,000 ppm)
2.0
2.1
2.2
2.3
2.4
Bulk density,
p b (g/cm 3 ) 25
2.6
2.7
2.8
2.9
3.0
APLC
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10 20 30 40
Corrected APS apparent limestone neutron porosity, <t> A pscor (P u -)
Purpose
This chart is used similarly to Chart Por-13 to determine the lithology
and porosity from Litho-Density* bulk density and APS* porosity log
curves (APLC or FPLC) in saltwater boreholes.
Example
Given:
Find:
Answer:
APLC porosity = 8 p.u. and bulk density = 2.2 g/cm 3 .
Approximate quartz sandstone porosity.
Enter 8 p.u. on the x-axis and 2.2 g/cm 3 on the y-axis to
And the intersection point is in the gas-in-formation cor-
rection region. Because the APLC porosity value was
used, move parallel to the blue gas correction line until
the blue quartz sandstone curve is intersected at approx-
imately 20 p.u.
228
Back to Contents
Porosity— LWD
adnVISI0N475* 4.75-in. Azimuthal Density Neutron Tool
Porosity and Lithology — Open Hole
Schlumberger
Por-15
1.9
FreshWater, Liquid-Filled Borehole (p,= 1.0g/cm 3 )
2.0
2.1
2.2
2.3
Bulk density,
Pb(g/cm 3 ) u
2.5
2.6
2.7
2.8
2.9
3.0
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5 5 10 15 20 25 30 35 40 45
Corrected apparent limestone neutron porosity, (|> AUNcor (p.u.)
Purpose
This chart is used to determine the crossplot porosity and lithology
from the adnVISION475 4.75-in. density and neutron porosity.
Description
Enter the chart with the adnVISION475 corrected apparent lime-
stone neutron porosity (from Chart Neu-31) and bulk density. The
intersection of the two values is the crossplot porosity. The position
of the point of intersection between the matrix curves represents the
relative percentage of each matrix material.
Example
Given: (|)ADNcor = 20 p.u. and pb = 2.24 g/cm 3 .
Find: Crossplot porosity and matrix material.
Answer: 25 p.u. in sandstone.
< ►
Back to Contents
229
Porosity— LWD
adnVISION675* 6.75-in. Azimuthal Density Neutron Tool
Porosity and Lithology — Open Hole
Schlumberger
Por-16
1.9
FreshWater, Liquid-Filled Borehole (p f = 1.0g/cm 3 )
2.0
2.1
2.2
2.3
Bulk density,
p„(g/cm 3 )
2.5
2.6
2.7
2.8
2.9
3.0
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5 5 10 15 20 25 30 35 40 45
Corrected apparent limestone neutron porosity, (|> ADNcor (p.u.)
Purpose Example
This chart uses the bulk density and apparent limestone porosity from Given:
the adnVISION 6.75-in. Azimuthal Density Neutron tool to determine
the lithology of the logged formation and the crossplot porosity. p m( j.
Description Answer:
This chart is applicable for logs obtained in freshwater drilling
fluid. Enter the corrected apparent limestone porosity and the bulk
density on the x- and y-axis, respectively. Their intersection point
determines the lithology and crossplot porosity.
Corrected adnVISION675 apparent limestone porosity =
20 p.u. and bulk density = 2.3 g/cm 3 .
Porosity and lithology type.
Entering the chart at 20 p.u. on the x-axis and 2.3 g/cm 3
on the y-axis corresponds to a crossplot porosity of
21.5 p.u. and formation comprising approximately
60% quartz sandstone and 40% limestone.
230
Back to Contents
Porosity— LWD
adnVISION825* 8.25-in. Azimuthal Density Neutron Tool
Porosity and Lithology — Open Hole
Schlumberger
Por-17
1.9
FreshWater, Liquid-Filled Borehole (p f = 1.0g/cm 3 )
2.0
2.1
2.2
2.3
Bulk density,
p b (g/cm 3 )
2.5
2.6
2.7
2.8
2.9
3.0
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© Schlumberger
5 5 10 15 20 25 30 35 40 4
Corrected apparent limestone neutron porosity, <|> ADNcor (p.u.)
5
Purpose
This chart is used similarly to Chart Por-15 to determine the lithology
and crossplot porosity from adnVISION825 8.25-in. Azimuthal Density
Neutron values.
< ►
Back to Contents
231
Porosity— LWD
EcoScope* 6.75-in. Integrated LWD Tool
Porosity and Lithology — Open Hole
Schlumberger
Por-18
1.9
FreshWater, Liquid-Filled Borehole (p f = 1.0g/cm 3 )
2.0
2.1
2.2
2.3
2.4
Bulk density,
p b (g/cm 3 )
2.5
2.6
2.7
2.8
2.9
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© Schlumberger
5 5 10 15 20 25 30 35 40 45
Corrected apparent limestone BPHI porosity (p.u.)
Purpose
This chart is used similarly to Chart Por-15 to determine the lithol-
ogy and crossplot porosity from EcoScope 6.75-in. density and best
thermal neutron porosity (BPHI) values.
Use this chart only with EcoScope BPHI neutron porosity; use
Chart Por-19 with EcoScope thermal neutron porosity (TNPH)
measurements.
232
< ►
Back to Contents
Porosity— LWD
EcoScope* 6.75-in. Integrated LWD Tool
Porosity and Lithology — Open Hole
Schlumberger
Por-19
1.9
FreshWater, Liquid-Filled Borehole (p f = 1.0g/cm 3 )
2.0
2.1
2.2
2.3
Bulk density,
Pb (g/cm3) 2A
2.5
2.6
2.7
2.8
2.9
3.0
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5 5 10 15 20 25 30 35 40 45
Corrected apparent limestone TNPH porosity (p.u.)
Purpose
This chart is used similarly to Chart Por-15 to determine the lithol-
ogy and crossplot porosity from EcoScope 6.75-in. density and ther-
mal neutron porosity (TNPH) values.
Use this chart only with EcoScope TNPH neutron porosity; use
Chart Por-18 with EcoScope best thermal neutron porosity (BPHI)
measurements.
< ►
Back to Contents
233
Porosity — Wireline
Sonic and Thermal Neutron Crossplot
Porosity and Lithology — Open Hole, Freshwater Invaded
Schlumberger
Purpose
This chart is used to determine crossplot porosity and an approxi-
mation of lithology for sonic and thermal neutron logs in freshwater
drilling fluid.
Description
Enter the corrected neutron porosity (apparent limestone porosity)
on the x-axis and the sonic slowness time (At) on the y-axis to find
their intersection point, which describes the crossplot porosity and
lithology composition of the formation. Two sets of curves are drawn
on the chart. The blue set of curves represents the crossplot porosity
values using the sonic time-average algorithm. The red set of curves
represents the field observation algorithm.
Example
Given:
Find:
Answer:
Thermal neutron apparent limestone porosity = 20 p.u.
and sonic slowness time = 89 |as/ft in freshwater
drilling fluid.
Crossplot porosity and lithology.
Enter the neutron porosity on the x-axis and the sonic
slowness time on the y-axis. The intersection point is at
about 25 p.u. on the field observation line and 24.5 p.u.
on the time-average line. The matrix is quartz sandstone.
234
< ►
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Porosity — Wireline
Sonic and Thermal Neutron Crossplot
Porosity and Lithology — Open Hole, Freshwater Invaded
Schlumberger
Por-20
(customary, former CP-2c)
t f =190u_s/ftandC ( = 0ppm
Sonic transit time,
At (us/ft)
110
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Field observation
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10 20 30 40
Corrected CNL* apparent limestone neutron porosity, 4> CNLcor (p.u.)
*Markof Schlumberger
© Schlumberger
< ►
Back to Contents
235
Porosity — Wireline
Sonic and Thermal Neutron Crossplot
Porosity and Lithology — Open Hole, Freshwater Invaded
Schlumberger
Por-21
(metric, former CP-2cm)
t, = 620 u.s/m and C f = ppm
Sonic transit time.
At (u.s/m)
sro
Ti
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Field observation
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10 20 30 40
Corrected CNL* apparent limestone neutron porosity, <() CNLcor (p.u.)
Purpose
This chart is used similarly to Chart Por-20 for metric units.
236
< ►
Back to Contents
Porosity — Wireline, LWD
Density and Sonic Crossplot
Porosity and Lithology — Open Hole, Freshwater Invaded
Schlumberger
Purpose
This chart is used to determine porosity and lithology for sonic and
density logs in freshwater-invaded zones.
Description
Enter the chart with the bulk density on the y-axis and sonic slow-
ness time on the x-axis. The point of intersection indicates the type
of formation and its porosity.
Example
Given: Bulk density = 2.3 g/cm 3 and sonic slowness
time = 82 us/ft.
Find: Crossplot porosity and lithology.
Answer: Limestone with a crossplot porosity = 24 p.u.
< ►
Back to Contents
continued on next page
237
Porosity — Wireline, LWD
Density and Sonic Crossplot
Porosity and Lithology — Open Hole, Freshwater Invaded
Schlumberger
Por-22
(customary, former CP-7)
t, = 189 us/ft and p, = 1.0 g/cm 3
1.8
Bulk density,
p b (g/cm 3 )
40 50 60 70 80 90 100
Sonic transit time. At (u.s/ft)
T
Field observation
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238
< ►
Back to Contents
Porosity — Wireline, LWD
Density and Sonic Crossplot
Porosity and Lithology — Open Hole, Freshwater Invaded
Schlumberger
Por-23
(metric, former CP-7m)
Bulk density,
p b (g/cm 3 )
© Schlumberger
1 R
t f = 620 u,s/m a nd p f = 1 .0 g/c m 3
1.9
2.0
2.1
2.2
2.3
2.4
2.5
2.6
2.7
2.R
2.9
3.0
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Anhydrite
150 200
250 300 350 400
Sonic transit time. At (u,s/m)
Purpose
This chart is used similarly to Chart Por-22 for metric units.
< ►
Back to Contents
239
Porosity — Wireline, LWD
Density and Neutron Tool
Porosity Identification — Gas-Bearing Formation
Schlumberger
Purpose Example
This chart is used to determine the porosity and average water satu- Given:
ration in the flushed zone (S xo ) for freshwater invasion and gas com-
position of C1.1H4.2 (natural gas). p m( j.
Description Answer:
Enter the chart with the neutron- and density-derived porosity values
((|)n and (|)d, respectively). On the basis of the table, use the blue curves
for shallow reservoirs and the red curves for deep reservoirs.
<|)d = 25 p.u. and (|)n = 10 p.u. in a low-pressure, shallow
(4,000-ft) reservoir.
Porosity and S xo .
Enter the chart at 25 p.u. on the y-axis and 10 p.u. on the
x-axis. The point of intersection identifies (on the blue
curves for a shallow reservoir) § = 20 p.u. and Sxo = 62%.
Depth
Pressure
Temperature
p w (g/cm 3 )
Ihw
p g (g/cm 3 )
'Hg
Shallow reservoir
-2,000 psi [-14,000 kPa]
~120°F[~50°C]
1.00
1.00
Deep reservoir
-7,000 psi [-48,000 kPa]
~240°F[~120°C]
1.00
1.00
0.25
0.54
Pw = density of water, p g = density of gas, l Hw = hydrogen index of water, and l Hg = hydrogen index of gas
240
< ►
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Porosity — Wireline, LWD
Density and Neutron Tool
Porosity Identification — Gas-Bearing Formation
Schlumberger
Por-24
(former CP-5)
50
40
30
Density-derived porosity,
D (p.u.)
20
10
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V
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7
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100
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For shallow reservoirs, use blue curves.
For deep reservoirs, use red curves.
h
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© Schlumberger
10 20 30 4(
Neutron-derived porosity, <j) N (p. u.)
)
< ►
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241
Porosity — Wireline
Density and APS* Epithermal Neutron Tool
Porosity Identification — Gas-Bearing Formation
Schlumberger
Purpose Example
This chart is used to determine the porosity and average water satu- Given:
ration in the flushed zone (S xo ) for freshwater invasion and gas com-
position of CH4 (methane). Find:
Description Answer:
Enter the chart with the APS Accelerator Porosity Sonde neutron- and
density-derived porosity values (<|)n and (|)d, respectively). On the basis
of the table, use the blue curves for shallow reservoirs and the red
curves for deep reservoirs.
<|)d = 15 p.u. and APS $$ = 8 p.u. in a normally pressured
deep (14,000-ft) reservoir.
Porosity and S xo .
<S> = 11 p.u. and S xo = 39%.
Depth
Pressure
Temperature
pw
Ihw
Pg
S
Shallow reservoir
-2,000 psi [-14,000 kPa]
~120°F[-50°C]
1.00
1.00
0.10
0.23
Deep reservoir
-7,000 psi [-48,000 kPa]
~240°F[~120°C]
1.00
1.00
0.25
0.54
p w = density of water, p g = density of gas, l Hw = hydrogen index of water, and ! Hg = hydrogen index of gas
242
< ►
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Porosity — Wireline
Density and APS* Epithermal Neutron Tool
Porosity Identification — Gas-Bearing Formation
Schlumberger
Por-25
(former CP-5a)
50
40
30
Density-derived porosity,
<t> D (p.u.)
20
10
40
40
2t
?5
)
Porosity
'40
6U
30
60
9^
80
20~
lb
ipn
4C
s
fin
°xo
20
80
20 J\
IUU
^xo
lb/'
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n
/P "^
F
"or shallow reservoirs, use blue curves.
w*
- For deep reservoirs, use red curves.
(
*Markof Schlumberger
© Schlumberger
) 10 20 30 4
APS epithermal neutron-derived porosity, <)> N (p.u.)
3
< ►
Back to Contents
243
Porosity — Wireline
Density, Neutron, and R xo Logs
Porosity Identification in Hydrocarbon-Bearing Formation — Open Hole
Schlumberger
Purpose
This nomograph is used to estimate porosity in hydrocarbon-bearing
formations by using density, neutron, and resistivity in the flushed
zone (Rxo) logs. The density and neutron logs must be corrected for
environmental effects and lithology before entry to the nomograph.
The chart includes an approximate correction for excavation effect,
but if hydrocarbon density (ph) is <0.25 g/cm 3 (gas), the chart may
not be accurate in some extreme cases:
■ very high values of porosity (>35 p.u.) coupled with medium
to high values of hydrocarbon saturation (Shi)
■ Shi- = 100% for medium to high values of porosity.
Description
Connect the apparent neutron porosity value on the appropriate
neutron porosity scale (CNL* Compensated Neutron Log or sidewall
neutron porosity [SNP] log) with the corrected apparent density
porosity on the density scale with a straight line. The intersection
point on the (])i scale indicates the value of ty\.
Draw a line from the <|)i value to the origin (lower right corner)
of the chart for Aty versus Shi-
Enter the chart with Shr from (Shi = 1 - S xo ) and move vertically
upward to determine the porosity correction factor (A(|)) at the inter-
section with the line from the §1 scale.
This correction factor algebraically added to the porosity <|)i gives
the corrected porosity.
Example
Given:
Find:
Answer:
Corrected CNL apparent neutron porosity = 12 p.u.,
corrected apparent density porosity = 38 p.u., and
Shi- = 50%.
Hydrocarbon-corrected porosity.
Enter the 12-p.u. ty mi value on the CNL scale. A line from
this value to 38 p.u. on the <|)Dcor scale intersects the (|)i
scale at 32.2 p.u. The intersection of a line from this
value to the graph origin and Shr = 50% is A§ = -1.6 p.u.
Hydrocarbon-corrected porosity: 32.2 - 1.6 = 30.6 p.u.
244
Back to Contents
Porosity — Wireline
Density, Neutron, and R xo Logs
Porosity Identification in Hydrocarbon-Bearing Formation — Open Hole
Schlumberger
Por-26
(former CP-9)
Tcor Tcor
(CNL*) (SNP)
50 50
H fDcor
>
-4
A0
(p.u.l
100 80 60 40 20
*Markof Schlumberger
© Schlumberger
< ►
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245
Porosity — Wireline
Hydrocarbon Density Estimation
Schlumberger
Por-27
(former CP-10)
s hr (%)
*Markof Schlumberger
© Schlumberger
s hr (%)
Purpose
This chart is used to estimate the hydrocarbon density (ph) within
a formation from corrected neutron and density porosity values.
Description
Enter the ratio of the sidewall neutron porosity (SNP) or
CNL* Compensated Neutron Log neutron porosity and density
porosity corrected for lithology and environmental effects
OsNPcor or <])cNLcor A]>Dcor, respectively) on the y-axis and the
hydrocarbon saturation on the x-axis. The intersection point of the
two values defines the density of the hydrocarbon.
Example
Given: Corrected CNL porosity = 15 p.u., corrected density
porosity = 25 p.u., and Shr = 30% (residual hydrocarbon).
Find: Hydrocarbon density.
Answer: Porosity ratio = 15/25 = 0.6. ph = 0.29 g/cm 3 .
246
Back to Contents
Saturation — Wireline, LWD
Porosity Versus Formation Resistivity Factor
Open Hole
Schlumberger
SatOH-1
(former Por-1)
50
40
30
25
20
15
10
9
8
Porosity, -,
<Mp.u.)
6
5
4
2.5
10
20
50
100
200
500 1,000
2,000 5,000
10,000
2.5
10
N
V
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ne ^
^^2.b
J>2_,2_5
)2.15
7 Fractures 1 ^
s?5 -
-fe- ::!
\ *<
*S,
^s^
^^S
s-2 2
^
s
v
^s,
\ 1.0
\
S~ 2u
\
l"B - a2
X
^
V
\
1.4
20
50 100 200 500 1,000
Formation resistivity factor, F R
2,000 5,000
10,000
© Schlumberger
Purpose
This chart is used for a variety of conversions of the formation
resistivity factor (Fr) to porosity.
Description
The most appropriate conversion is best determined by laboratory
measurement or experience in the area. In the absence of this
knowledge, recommended relationships are the following:
■ Soft formations (Humble formula): F R = 0.62/c> 2 - 51 or F r = 0.81A]) 2
■ Hard formations: Fr = l/(]) m with the appropriate cementation
factor (m).
Example
Given:
Soft formation with
Hard formation (m = 2) with
if = 25 p.u.
i) = 8 p.u.
Find:
Fr.
Fr.
Answer:
Fr = 13 (from chart).
Fr = 160 (from chart).
Fr = 12.96 (calculated).
Fr = 156 (calculated).
< ►
Back to Contents
247
Saturation — Wireline, LWD
Spherical and Fracture Porosity
Open Hole
Schlumberger
SatO H -2
(former Por-1a)
Cementation
exponent, m
0.5 0.8 1
Isolated
pores
Fractures
4 6
Porosity, <)> (p.u. I
40 50
© Schlumberger
Purpose
This chart is used to identify how much of the measured porosity
is isolated (vugs or moldic) or fractured porosity.
Description
This chart is based on a simplified model that assumes no contribu-
tion to formation conductivity from vugs and moldic porosity and the
cementation exponent (m) of fractures is 1.0.
When the pores of a porous formation have an aspect ratio close
to 1 (vugs or moldic porosity), the value of m of the formation is usu-
ally greater than 2. Fractured formations typically have a cementa-
tion exponent less than 2.
Enter the chart with the porosity ((])) on the x-axis and m on the
y-axis. The intersection point gives an estimate of either the amount
of isolated porosity (c|)iso) or the amount of porosity resulting from
fractures (§&).
Example
Given:
Find:
Answer:
tj> = 10 p.u. and cementation exponent = 2.5.
Intergranular (matrix) porosity.
Entering the chart with 10 p.u. and 2.5 gives an intersec-
tion point of tpiso = approximately 4.5 p.u.
Intergranular porosity = 10 - 4.5 = 5.5 p.u.
248
Back to Contents
Saturation — Wireline, LWD
Saturation Determination
Open Hole
Schlumberger
Purpose
This nomograph is used to solve the Archie water saturation
equation:
s -K-
w V R t \
F R R w
where
Sw =
water saturation
R =
resistivity of clean-water formation
Rt =
true resistivity of the formation
Fr =
formation resistivity factor
Kw —
formation water resistivity.
Description
If R is known, a straight line from the known R value through the
measured Rt value indicates the value of Sw. If Ro is unknown, it may
be determined by connecting R w with Fr or porosity ((])).
Example
Given:
Find:
Answer:
It should be used in clean (nonshaly) formations only.
R w = 0.05 ohm-m at formation temperature, ty = 20 p.u.
(Fr = 25), and R t = 10 ohm-m.
Water saturation.
Enter the nomograph on the R w scale at R w = 0.05 ohm-m.
Draw a straight line from 0.05 through the porosity scale
at 20 p.u. to intersect the R scale.
From the intersection point of R = 1, draw a straight line
through Rt = 10 ohm-m to intersect the Sw scale.
Sw = 31.5%.
< ►
Back to Contents
continued on next page
249
Saturation — Wireline, LWD
Saturation Determination
Open Hole
Schlumberger
SatO H -3
(former Sw-1)
Clean Formations, m = 2
R w
(ohm-m)
_ 0.01
J 1 0.02
0.03
0.04
J L 0.05
0.06
0.07
0.08
0.09
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
1.5
2
(%)
^ 2,000
2.5 _
3 _
1 1,000
1 800
4_
1 600
5 _
1 400
6 -
- 300
7 _
. 200
8 _
9 _
10 -
1 100
1 80
I 60
15 J
50
40
20 J
30
1 20
25 J
30 J
1 10
35 J
8
40 _
6
45
: 5
50 J
L 4
m = 2.0
Ro
(ohm-m)
30 __
20
18
16
14
12
10
9
8
7
6
5
4
3 _.
2
1.8
1.6
1.4
1.2
1.0
0.9
0.8
0.7
0.6
0.5
0.4
0.3 _.
0.2
0.18
0.16
0.14
0.12
0.10 _L
R,
(ohm-m)
10,000 _
8,000 I
6,000 JL
5,000 _-
4,000 --
3,000 _.
2,000 _.
1,000
800
600
500
400
300
200
100
80
60
50
40
30
20
10
8
6
5
4
3
1.0
0.8
0.6
0.5
0.4
0.3
0.2 ±
0.1 J_
(%)
5
6 _.
9 _.
10
11
12
13
14
15
16
18
20
25
30
40
50
60
70
80
90
100
© Schlumberger
FrR«
250
< ►
Back to Contents
Saturation — Wireline, LWD
Saturation Determination
Open Hole
Schlumberger
Purpose
This chart is used to determine water saturation (Sw) in shaly or
clean formations when knowledge of the porosity is unavailable. It
may also be used to verify the water saturation determination from
another interpretation method. The large chart assumes that the
mud filtrate saturation is
IS
The small chart provides an Sxo correction when S xo is known.
However, water activity correction is not provided for the SP portion
of the chart (see Chart SP-2).
Description
Clean Sands
Enter the large chart with the ratio of the resistivity of the flushed
zone to the true formation resistivity (R xo /Rt) on the y-axis and the
ratio of the resistivity of the mud filtrate to the resistivity of the for-
mation water (Rmf /R w ) on the x-axis to find the water saturation at
average residual oil saturation (Sw a ). If Rmf/Rw is unknown, the chart
may be entered with the spontaneous potential (SP) value and the
formation temperature. If S xo is known, move diagonally upward,
parallel to the constant-Swa curves, to the right edge of the chart.
Then, move horizontally to the known S xo (or residual oil saturation
[ROS], S or ) value to obtain the corrected value of Sw.
Example
Given:
Find:
Answer:
R xo = 12 ohm-m, Rt = 2 ohm-m, Rmf/Rw = 20, and
Sor — 20/o.
Sw (after correction for ROS).
Enter the large chart at R xo /Rt = 12/2 = 6 on the
y-axis and Rmf/Rw = 20 on the x-axis. From the point of
intersection (labeled A), move diagonally to the right to
intersect the chart edge and directly across to enter the
small chart and intersect S or = 20%.
Sw = 43%.
Description
Shaly Sands
Enter the chart with R xo /Rt and the SP in the shaly sand (Epsp). The
point of intersection gives the Swa value. Draw a line from the chart's
origin (the small circle located at R xo /Rt = Rmf/Rm = 1) through this
point to intersect with the value of static spontaneous potential (Essp)
to obtain a value of R xo /Rt corrected for shaliness. This value of R xo /Rt
versus Rmf/Rw is plotted to find Sw if Rmf/Rw is unknown because the
point defined by R xo /Rt and Essp is a reasonable approximation of Sw.
The small chart to the right can be used to further refine Sw if S or is
known.
Example
Given: R xo /R t = 2.8, Rmf/Rw = 25, E PS p = -75 mV, Essp = -120 mV,
and electrochemical SP coefficient (Kc) = 80 (formation
temperature = 150°F).
Find: Sw and corrected value for S or = 10%.
Answer: Enter the large chart at R xo /Rt = 2.8 and the intersection
of Epsp = -75 mV at Kc = 80 from the chart below. A line
from the origin through the intersection point (labeled B)
intersects the -120-mV value of Essp at Point C. Move
horizontally to the left to intersect Rmf/Rw = 25 at Point D.
Then move diagonally to the right to intersect the right
y-axis of the chart. Move horizontally to the small chart to
determine S xo = 0.9%, Sw = 38%, and corrected Sw = 40%.
For more information, see Reference 12.
< ►
Back to Contents
continued on next page
251
Saturation — Wireline, LWD
Saturation Determination
Open Hole
Schlumberger
SatO H -4
(former Sw-2)
s or (%)
Rmf/Rw
10 20 30 40
0.6 U.8 l.U l.b
1 2.b 3 4 b 6 8 10 lb
2U 2b 30 40 bO 60
2
$>'
/
50
40
30
20
10
8
6
5
4
3
R xc, „
R,
1
0.8
0.6
0.5
0.4
0.3
0.2
0.1
0.08
75
100 .
Temperature 150
(°F) 200 ;
300 :
© Schlumberger
80
70
60
4>'
y \y
y \
' \
y 1
R.n
fc PSP = -Mog-^-2
K c log ^
™t
50
S>'
\
\
Sxo = V^w
40
30
25
20
15
10
4
&
/
- C
■-,■*■*
A;:$I#-
C^Z
TSJt
!?V
£y
ic^
Zv?\°.^
B
sty
M
c\\ci y
t
iS>
*^ 1
i
,»\«
> /
t>
1.(
I 0.9 0.8 0.7
6
tff
/
'vj.
S xo
°w _ °xol°wa'
. 25
50 T
7r . Temperature
! 100 ( ° c)
150
$
•> /
<^
,
0.6
8
r
7
1
8
r
1.0 1.5
2 2.5 3 4 5 6 8
Rmf/Rw
10 15
20 25 30
40 50 60
V*\
n
' ////// / / / / / / /
/ / / / / s*
\\\
\ 1 1 i /;////////x/^<y>'^
\Vri
\ l \lili//////////X////^/^^
20 10
c
-20 -40 -60 -80 -100 -120 -140
Ep SP orE SS p(mV)
252
< ►
Back to Contents
Saturation — Wireline, LWD
Graphical Determination of S w from S w t and S W b
Open Hole
Schlumberger
SatOH-5
(former Sw-14)
100
90
80
70
60
S wt (%) 50
40
30
20
10
^wb
70%
|
60%
"*
%
bU
40%
1 .
30%
20%
r 1
10%
u
C
© Schlumberger
10 20 30 40 50 60 70 80 90 100
s w (%)
Purpose
This chart is used to drive a value of water saturation (Sw) corrected
for the bound-water volume in shale.
Description
This is a graphical determination of Sw from the total water satura-
tion (Swt) and the saturation of bound water (Swb):
"wt ^wb
Enter the y-axis with Swt and move horizontally to intersect
the appropriate Swb curve. Read the value of Sw on the x-axis.
Example
Given: Swt = 45% and Swb = 10%.
Find: Sw.
Answer: Sw = 39.5%.
1-S
">yi •
Back to Contents
253
Saturation — Wireline, LWD
Porosity and Gas Saturation in Empty Hole
Open Hole
Schlumberger
SatO H -6
(former Sw-11)
Us8 if no
shale present
Neutron
porosity
index
(corrected
for lithology)
/latrix density, 2.75
Pma(g/cm 3 )
Density and Hydrogen Index of Gas Assumed Zero
Porosity, <]) (p.u.)
10 12 14 16 18 20 22 24 26
28 30
Use if no
oil present
_ 10,000
IC 4,000
-- 2,000
zz 1,000
II 400
-- 300
II 200
__ 150
100
70
-L 60
:: 50
II 40
__ 30
:: 20
II 15
X 14
13
__ 12
__ 11
Sandstone
Limy sandstone
Limestone
Dolomite
© Schlumberger
2.7 2.6 2.5 2.4 2.3 2.2 2.1
Apparent bulk density from density log, p b (g/cm 3 )
Purpose
This chart is used to determine porosity ((])) and gas saturation (Sg)
from the combination of density and neutron or from density and
resistivity measurements.
Example
Given:
Find:
Answer:
S„ =
Sw :
Sh-Sg
100 - s h .
Description
Enter from the point of intersection of the matrix density (pma) and
apparent bulk density (pb). Move vertically upward to intersect
either neutron porosity ((|)n, corrected for lithology) or the ratio of
true resistivity to connate water resistivity (Rt/R w ). This point defines
the actual porosity and Sg on the curves.
Oil saturation (S ) can also be determined if all three measure-
ments (density, neutron, and resistivity) are available. Find the values
of § and Sg as before, and then find the intersection of Rt/R w with (])
to read the value of the total hydrocarbon saturation (Sh) on the
saturation scale for use in the following equations:
254
a ► Back to Contents
Limy sandstone (p ma = 2.68 g/cm 3 ), pb = 2.44 g/cm 3 ,
<|>n = 9 p.u., Rt = 74 ohm-m, and R w = 0.1 ohm-m.
§, S g , S h , So, and Sw.
First, find R t /R w = 74/0.1 = 740.
c> = 12 p.u. and S g = 25%.
Sh = 70% (total hydrocarbon saturation).
So = 70 - 25 = 45%.
Sw = 100 - 70 = 30%.
Saturation — Wireline
EPT* Propagation Time
Open Hole
Schlumberger
SatO H -7
(former Sxo-1)
21
20
19
18
17
16
15
14
tp.lns/m) 13
12
11
10
9
10.9.
6
5
Sandstone
tpma (ns/m)
8 9 10
■ l.l.i
tpm= (ns/m)
8 9
■ l.l
10
_l
\\\
\
\\\
\
\\\
\
\
\
^A
\
\
\\\
\
\
\\\
\
\
V\>
\
\\\
\
\
\\\
\
\\\
\
\
\N\
\
\
\
\\\
\
\
^
\
olomitG
Limestone
Sandstone
Dolomite
S„
%)
100
_90
_80
_60
_40
_30
_ 20
I—
Limestone
*Markof Schlumberger
© Schlumberger
Purpose
This nomograph is used to define flushed zone saturation (S xo ) in
the rock immediately adjacent to the borehole by using the EPT
Electromagnetic Propagation Tool time measurement (t p i).
Description
Use of this chart requires knowledge of the reservoir lithology or
matrix propagation time (t pma ), saturating water propagation time
(t pw ), porosity ((])), and expected hydrocarbon type. Enter the far- left
scale with t p i and move parallel to the diagonal lines to intersect the
appropriate t pma value. From this point move horizontally to the right
edge of the scale grid. From this point, extend a straight fine through
the porosity scale to the center scale grid; again, move parallel to the
diagonal lines to the appropriate t pma value and then horizontally to
the right edge of the grid scale. From this point, extend a straight
line through the intersection of t pw and the hydrocarbon type point
to intersect the S xo scale. For more information, see Reference 25.
Back to Contents
255
Saturation — Wireline
EPT* Attenuation
Open Hole
Schlumberger
SatO H -8
(former Sxo-2)
c
xo
(%)
5
A„
_ 6
(dB/m)
_ 7
6,000
_ 8
5,000 _
"EPTcor
(dB/m)
_ 9
_ 10
4,000 _
1
3,000 _
*
.._ 2
(p.u.)
-
2,000 _
.._ 3
_ 20
.1
.._ 4
I 6
'"" 8
2
_ 30
1,000 _
3
J
- 10
900 _
4
_ 40
800 _
.5
700 _
20
600 _
_ 50
\ —
.10
30
500 _
400 _
\^
.15
.20
40 yT
60 y^
_ 60
_ 70
_ 80
300 _
^30
140
80 y^
"— 100/
_ 90
_ 100
200 _
200
300
400
100 _
600
90 _
800
*Markof Schlumberger
80 _
-— 1,000
© Schlumberger
Purpose
This nomograph is used to determine the flushed zone saturation
(Sxo) in the rock immediately adjacent to the borehole by using the
EPT Electromagnetic Propagation Tool attenuation measurement. It
requires knowledge of the saturating fluid (usually mud filtrate)
attenuation (A w ), porosity ((])), and the EPT EATT attenuation
(Aeptcoi) corrected for spreading loss.
Description
The value of A w must first be determined. Chart Gen- 16 is used to
estimate A w by using the equivalent water salinity and formation
temperature. EPT-D spreading loss is determined from the inset on
Chart Gen-16 based on the uncorrected EPT propagation time (t p i)
measurement. The spreading loss correction algebraically added to
the EPT-D EATT attenuation measurement gives the corrected EPT
attenuation (Aeptcoi). These values are used with porosity on the
nomograph to determine S xo .
Example
Given:
Find:
Answer:
EATT = 250 dB/m, t p i = 10.9 ns/m, (b = 28 p.u., water salin-
ity = 20,000 ppm, and bottomhole temperature = 150°F.
Spreading loss (from Chart Gen-16 inset) and S xo .
The spreading loss determined from the inset on
Chart Gen-16 is -82 dB/m.
Aeptcoi- = 250 - 82 = 168 dB/m.
A w (from Chart Gen-16) = 1,100 dB/m.
Enter the far- left scale at A w = 1,100 dB/m and draw
a straight line through § = 28 p.u. on the next scale to
intersect the median line. From this intersection point,
draw a straight line through Aeptcoi = 168 dB/m on the
next scale to intersect the S xo value on the far-right
scale. Sxo = 56 p.u.
256
Back to Contents
Saturation — Wireline
Capture Cross Section Tool
Cased Hole
Schlumberger
Purpose
This chart is used to determine water saturation (Sw) from capture
cross section, or sigma (E), measurements from the TDT* Thermal
Decay Time pulsed neutron log.
Description
This chart uses sigma water (E w ), matrix capture cross section (E ma ),
and porosity ((])) to determine water saturation in clean formations.
The chart may be used in shaly formations if sigma shale (E S h), the
volume fraction of shale in the formation (Vsh), and the porosity cor-
rected for shale are known.
Thermal decay time (t and t S h in shale) is also shown on some
of the chart scales because it is related to E.
Procedure
Clean Formation
The Sw determination for a clean formation requires values known
for E ma (based on lithology), ty, E w from the NaCl salinity (see Chart
Gen-12 or Gen-13), and sigma hydrocarbon (Eh) (see Chart Gen-14).
Enter the value of E ma on Scale B and draw a line to Pivot Point B.
Enter Ei g on Scale B and draw Line b through the intersection of
Line a and the value of § to intersect the sigma of the formation
fluid (Ef) on Scale C. Draw Line 5 from Ef through the intersection
of Eh and E w to determine the value of Sw on Scale D.
Example: Clean Formation
Given: Ei og = 20 c.u., E ma = 8 c.u. (sandstone) from TDT tool,
E h = 18 c.u., E„ = 80 c.u. (150,000 ppm or mg/kg), and
<j> = 30 p.u.
Find: Sw.
Answer: Following the procedure for a clean formation, Sw = 43%.
Procedure
Shaly Formation
The Sw determination in a shaly formation requires additional infor-
mation: sigma shale (E S h) read from the TDT log in adjacent shale,
V S h from porosity-log crossplot or gamma ray, shale porosity ((|) S h) read
from a porosity log in adjacent shale, and the porosity corrected for
shaliness ((])shcor) with the relation for neutron and density logs
in liquid-filled formations of (|)shcor = <|>iog - V S h(|)sh.
Enter the value of E ma on Scale B and draw Line 1 to intersect
with Pivot Point A. From the value of E S h on Scale A, draw Line 2
through the intersection of Line 1 and V S h to determine the shale-
corrected E cor on Scale B. Draw Line 3 from E CO r to the value of E ma
on the scale to the left of Scale C. Enter Ei og on Scale B and draw
Line 4 through the intersection of Line 3 and the value of (]) to deter-
mine Ef on Scale C. From Ef on Scale C, draw Line 5 through the
intersection of Eh and Ew to determine Swon Scale D.
Example
Given:
Eiog = 25 c.u.
E ma = 8 c.u.
Eh = 18 c.u.
E w = 80 c.u.
E S h = 45 c.u.
(|>iog = 33 p.u.
c>sh = 45 p.u.
V sh = 0.2.
Find:
(|)shcor and Sw.
Answer:
First find the porosity corrected for shaliness,
(|>shcor = 33 p.u. - (0.2 x 45 p.u.) = 24 p.u. This value
is used for the (]) point between Scales B and C.
Sw = 43%.
< ►
Back to Contents
continued on next page
257
Saturation — Wireline
Capture Cross Section Tool
Cased Hole
Schlumberger
SatCH-1
(former Sw-1 2)
25 <h(p.u.)
Qf Pivot point B /
f/
5 1Q. '15 20 30 40 .50 60 70 80 90 100 110 120
C *x„„\ i i i i i . f i i i i i i i i i i i i i i i
*0
So
e \ £ w (cu.)
*^£&9&:
X?<fc
^^<^
nKa/(?
&^*
o^>^?^
V
^<$*&>
Formation water
salinity (ppm x 1,000)
2h(c.u'
S w (%) \
100 90 80 70 60 50 \ 40 30 20 10
D I I I I | I I I I I | l M I I I I I I I I
Igtog ~ Z ma ) - <t>(S h - 2 ma ) - V sh (Z sh - 2 n
<|)(2w-2h)
© Schlumberger
258
< ►
Back to Contents
Saturation — Wireline
Capture Cross Section Tool
Cased Hole
Schlumberger
Purpose
This chart is used to graphically interpret the TDT* Thermal Decay
Time log. In one technique, applicable in shaly as well as clean
sands, the apparent water capture cross section (E wa ) is plotted
versus bound-water saturation (Swb) on a specially constructed grid to
determine the total water saturation (Swt).
Description
To construct the grid, refer to the example chart on this page. Three
fluid points must be located: free-water point (Ewt), hydrocarbon
point (Eh), and a bound-water point (Ewb). The free- (or connate for-
mation) water point is located on the left y-axis and can be obtained
from measurement of a formation water sample, from Charts Gen-12
and Gen-13 if the water salinity is known, or from the TDT log in
a clean water-bearing sand by using the following equation:
(1)
<\>
The hydrocarbon point is also located on the left y-axis of the grid.
It can be determined from Chart Gen-14 based on the known or
expected hydrocarbon type.
The bound-water point (Swb) can be obtained from the TDT log
in shale intervals also by using the E wa equation. It is located on the
right y-axis of the grid.
The distance between the free-water and hydrocarbon points is
linearly divided into lines of constant water saturation drawn parallel
to a straight line connecting the free-water and bound-water points.
The Swt = 0% line originates from the hydrocarbon point, and the
Swt = 100% line originates from the free-water point.
The value of E wa from the equation is plotted versus Swb to give
Swt- The value of Swb can be estimated from the gamma ray or other
bound-water saturation estimator.
Once Swt and Swb are known, the water saturation of the reservoir
rock exclusive of shale can be determined using
wt
K- !_ s
J \b
(2)
wb
Example
Given:
Find:
Answer:
Ewt = 61 c.u. and Eh = 21 c.u. (medium-gravity oil with
modest GOR from Chart Gen-14), and £ W b = 76 c.u.
(from TDT log in a shale interval and the preceding Eq. 1).
Swt and Sw for Point 4.
Zwa = 54 c.u. (from Eq. 1) and Swb = 25% (from
gamma ray).
Swt = 72% and Sw = 63% (from the preceding Sw
equation).
■^wa
(c.u.:
40
*Markof Schlumberger
© Schlumberger
40 60
s„„(%)
- 1 — i — i — i — i — i — i — i — i — i
44 48 52 56 60 64 68 72 76 80
Gamma Ray
(gAPl)
The grid can also be used to graphically determine water
saturation (Sw) in clean formations by crossplotting Ei g on the
y-axis and porosity (<|>) on the x-axis. The values of E ma and Sw need
not be known but must be constant over the interval studied. There
must be some points from 100% water zones and a good variation in
porosity. These water points define the Sw = 100% line; when extrap-
olated, this line intersects the zero-porosity axis at E ma . The Sw = 0%
line is drawn from E ma at tj) = p.u. to E = Eh at ty = 100 p.u. (or
E = Vt(Ema + Eh) at <|> = 50 p.u.). The vertical distance from Sw = 0%
to Sw = 100% is divided linearly to define lines of constant water
saturation. The water saturation of any plotted point can thereby
be determined.
< ►
Back to Contents
continued on next page
259
Saturation — Wireline
Capture Cross Section Tool
Cased Hole
Schlumberger
SatCH-2
(former Sw-17)
■Hog
or
<t> or S wh
i
© Schlumberger
260
< ►
Back to Contents
Saturation — Wireline
Schlumberger
RST* Reservoir Saturation Tool — 1.6875 in. and 2.5 in.
Carbon/Oxygen Ratio — Open Hole
Purpose consistently outside the trapezoid, the interpretation model may
Charts SatCH-3 through SatCH-8 are presented for illustrative require revision.
purposes only. They are used to ensure that the measured near- and The rectangle within each chart is constructed from four distinct
far-detector carbon/oxygen (C/O) ratio data are consistent with the points determined by the intersection of the near- and far-detector
interpretation model. These example charts are drawn for specific C/O ratios:
cased and open holes and tool sizes to provide trapezoids for the WW = water/water point
to determination of oil saturation (S ) and oil holdup (y ). WO = water/oil point
Description ow = oil/water point
Known formation and borehole data define the expected C/O ratio 00 = oil/oil point.
values, which are determined in water saturation and borehole RST Reservoir Saturation Tool processing then determines the water
holdup values ranging from to 1. All log data for formations with saturation (S*) of the formation.
porosity ((])) greater than 10 p.u. should be within the trapezoidal
area bounded by the limits of the S and y values. If data plot
Back to Contents
continued on next page
261
Saturation — Wireline
RST* Reservoir Saturation Tool — 1.6875 in. and 2.5 in.
in 6.125-in. Borehole
Carbon/Oxygen Ratio — Open Hole
Schlumberger
SatCH-3
(former RST-3)
<(> = 30%, 6.125-in. Open HoIg
Far-detector
carbon/oxygen 0A
ratio
f)R
RST-A and RST-C, limestone
RST-A, quartz sandstone
RST-B and RST-D, limestone
RST-B, quartz sandstone
00
or
<»00
0.4
WO
^ ^*oo
00
n?
WO __->
>^JT0W
•
ow
+*
*"
/wwTWW
n
WV^
- *~
WW
0.5
Near-detector carbon/oxygen ratio
1.0
(|) = 20%, 6.125-in. Open Hole
Far-detector
carbon/oxygen 0.4
ratio
OR
RST-A and RST-C, limestone
RST-A, quartz sandstone
RST-B and RST-D, limestone
RST-B, quartz sandstone
06
^00
04
■^\j*m
• 00
wo*
•oo
00
0?
W0-
WW /£
•
ow
•
W0 # # 0^''
W0 -.''''WW
•ow
4
Y"WN
WW
0.5
Near-detector carbon/oxygen ratio
1.0
*Markof Schlumberger
© Schlumberger
262
< ►
Back to Contents
Saturation — Wireline
RST* Reservoir Saturation Tool — 1.6875 in. and 2.5 in.
in 9.875-in. Borehole
Carbon/Oxygen Ratio — Open Hole
Schlumberger
SatCH-4
c|) = 30%, 9.875-in. Open Hole
Far- detector
carbon/oxygen
ratio
1.5
RST-AandRST-C, limestone
RST-A, quartz sandstone
RST-B and RST-D, limestone
RST-B, quartz sandstone
00
1 n
^-^Z^\m
00
n^i
WO
/WO
V\
g
n
WW 1
"tow
0.5 1.0
Near-detector carbon/oxygen ratio
1.5
4> = 20%, 9.875-in. Open Hole
Far-detector
carbon/oxygen
ratio
1.5
RST-AandRST-C, limestone
RST-A, quartz sandstone
RST-Band RST-D, limestone
RST-B, quartz sandstone
1 n
^^•oo
05
J,^' „» ^
. + ' oo
wo
. — •-"ow
n
wv
u.-^- - " " "
WW
0.5 1.0
Near-detector carbon/oxygen ratio
1.5
*Markof Schlumberger
© Schlumberger
< ►
Back to Contents
263
Saturation — Wireline
RST* Reservoir Saturation Tool — 1.6875 in. and 2.5 in.
in 8.125-in. Borehole with 4.5-in. Casing at 11.6 Ibm/ft
Carbon/Oxygen Ratio — Cased Hole
Schlumberger
SatCH-5
(former RST-5)
ctj = 30%, 6.125-in. Borehole, 4.5-in. Casing at 11. 6 Ibm/ft
0.8
0.6
RST-AandRST-C, limestone
RST-A, quartz sandstone
RST-B and RST-D, limestone
RST-B, quartz sandstone
Far-detector
carbon/oxygen 0.4
ratio
0.2
Near-detector carbon/oxygen ratio
<|> = 20%, 6.125-in. Borehole, 4.5-in. Casing at 1 1.6 Ibm/ft
Far-detector
carbon/oxygen 0.4
ratio
OR
RST-A and RST-C, limestone
RST-A, qnart7 sanrktnnp
RST-B and RST-D, limestone
RST-B, quartz sandstone
or
04
^•oo
WO
— pr^^jtfm/
?»00
n?
WO/JP
-wfl__*1)W
ow ,''
n
WW
F
-■•bw
WW
0.5
Near-detector carbon/oxygen ratio
1.0
*Markof Schlumberger
© Schlumberger
264
< ►
Back to Contents
Saturation — Wireline
RST* Reservoir Saturation Tool — 1.6875 in. and 2.5 in.
in 7.875-in. Borehole with 5.5-in. Casing at 17 Ibm/ft
Carbon/Oxygen Ratio — Cased Hole
Schlumberger
SatCH-6
Far-detector
carbon/oxygen
ratio
Far-detector
carbon/oxygen
ratio
*Markof Schlumberger
© Schlumberger
0.8
0.6
0.4
0.2
0.8
0.6
0.4
0.2
q) = 30%, 7.875-in. Borehole, 5.5-in. Casing at 17 Ibm/ft
RST-A and RST-C, limestone
RST-A, quartz sandstone
RST-B and RST-D, limestone
RST-B, quartz sandstone
00
^/^0W
>00
WO*
S £
pmy^
*^- * ^owl— —
nw j- '
V
wo^/yp^^;
WO Ifc^f^'
A/V 'WW
m
•
•
•
WW (
'/*' -----
ow
wwf
1
0.5
Near-detector carbon/oxygen ratio
<]> = 20%, 7.875-in. Borehole, 5.5-in. Casing at 17 Ibm/ft
1.0
RST-A and RST-C, limestone
RST-A, quartz sandstone
RST-B and RST-D, limestone
RST-B, quartz sandstone
J»00
^Tow
^^f^uv
. — - — 37*00
wo^^--^;
W0/^<^<
s^'1*Wi
" ^'l— — .
— -«™ nn
WW \^f^""' "
•
s
s
•
W
WW,
V U *» s ^ *
0/*>' -----
if-"'
- - —
ow
WW
0.5
Near-detector carbon/oxygen ratio
1.0
-* ►
Back to Contents
265
Saturation — Wireline
RST* Reservoir Saturation Tool — 1.6875 in. and 2.5 in.
in 8.5-in. Borehole with 7-in. Casing at 29 Ibm/ft
Carbon/Oxygen Ratio — Cased Hole
Schlumberger
SatCH-7
(former RST-1)
$ = 30%, 8.5-in. Borehole, 7-in. Casing at 29 Ibm/ft
Far-detector
carbon/oxygen 0.4
ratio
OR
RST-Aand RST-C, limestone
RST-A, quartz sandstone
00
RST-B and RST-D, limestone
RST-B, quartz sandstone
^o
OR
* *
00
0.4
* "^ 1
/ 00
0?
W0« — " s
">^)W
•'OW
n
WW <^ "
wwir'"""
*■
WW
0.5
Near-detector carbon/oxygen ratio
: 20%, 8.5-in. Borehole, 7-in. Casing at 29 Ibm/ft
1.0
Far-detector
carbon/oxygen 0-4
ratio
08
RST-Aand RST-C, limestone
RST-A, qnart7 sanrktnnp
RST-B and RST-D, limestone
RST-B, quartz sandstone
00
or
^^<*»
ow
04
^S^-'*' 00
<>"'-«'nw ■
00
««•_, — .. — — — —"~
ow^X
00
A —
n?
*
WW/ ir^r<r:
W0*2^^-""
*
n
WW
*",-—
{'-'"'
--""""
WW*
WW
0.5
Near-detector carbon/oxygen ratio
1.0
*Markof Schlumberger
© Schlumberger
266
< ►
Back to Contents
Saturation — Wireline
RST* Reservoir Saturation Tool — 1.6875 in. and 2.5 in.
in 9.875-in. Borehole with 7-in. Casing at 29 Ibm/ft
Carbon/Oxygen Ratio — Cased Hole
Schlumberger
SatCH-8
(former RST-2)
4> = 30%, 9.875-in. Borehole, 7-in. Casing at 29 Ibm/ft
Far-detector
carbon/oxygen 0.4
ratio
OR
RST-A and RST-C, limestone
RST-A, quartz sandstone
RST-B and RST-D, limestone
RST-B, quartz sandstone
nn
OR
^S"^ ^t^S
1\A
*00
' 03
04
-?*^ow
/ 00
/-- -*
0?
wo — -^y"
ow y
WO
wo/v^:
•
ow
n
W\
WW
■ —"■"""
^ *" ' ' "
WW
9
0.5
Near-detector carbon/oxygen ratio
<s> = 20%, 9.875-in. Borehole, 7-in. Casing at 29 Ibm/ft
1.0
Far-detector
carbon/oxygen 0-4
ratio
08
RST-A and RST-C, limestone
RST-A, quartz sandstone
RST-B and RST-D, limestone
RST-B, quartz sandstone
jp00
OR
>/ ^0^\ «■»■•
[ow
00
04
^00
n i
wo ^--^T^s
* ■* ,11' — ■"*
•ow jt oo
V
\Xwoxv^--,
vwPj|£f^T-
^. — , ,. • ■* ■""■
*
ow
w
WW,
- — — -"
1
WW
0.5
Near-detector carbon/oxygen ratio
1.0
*Markof Schlumberger
© Schlumberger
< ►
Back to Contents
267
Permeability
Permeability from Porosity and Water Saturation
Open Hole
Schlumberger
Purpose
Charts Perm-1 and Perm-2 are used to estimate the permeability of
shales, shaly sands, or other hydrocarbon-saturated intergranular
rocks at irreducible water saturation (Swi).
Description
The charts are based on empirical observations and are similar in
form to a general expression proposed by Wyllie and Rose (1950)
(see Reference 49):
1/2
-c.
(1)
Chart Perm-1 presents the results of one study for which the
observed relation was
f
1/2
lOO^)
2.25 ^
(2)
Chart Perm-2 presents the results of another study:
k 1/2 70(b 2 :
1-S„
\
(3)
The charts are valid only for zones at irreducible water saturation.
Enter porosity (§) and S™ on a chart. Their intersection defines
the intrinsic (absolute) rock permeability (k). Medium-gravity oil is
assumed. If the saturating hydrocarbon is other than medium-gravity
oil, a correction factor (C) based on the fluid densities of water and
hydrocarbons (p w and ph, respectively) and elevation above the free-
water level (h) should be applied to the Swi value before it is entered
on the chart. The chart on this page provides the correction factor
based on the capillary pressure:
P,
h (pw"Ph)
2.3
(4)
Charts Perm-1 and Perm-2 can be used to recognize zones at irre-
ducible water saturation, for which the product c^S™ from levels within
the zone is generally constant and plots parallel to the c^S™ lines.
Example
Given: (]) = 23 p.u., Swi = 30%, gas saturation with ph = 0.3 g/cm 3
and p w = 1.1 g/cm 3 , and h = 120 ft.
Find: Correction factor and k.
Answer: First, find p c to determine the correction factor if the
zone of interest is not at irreducible water saturation:
h(pw-Ph) 120(1.1-0.3)
2.3
2.3
:42.
Enter the correction factor chart with S™ = 30% to inter-
sect the curve for p c = 40 (nearest to 42), for which the
correction factor is 1.08. The corrected Swi value is Swi =
1.08 x 30% = 32.4%.
Chart Perm-1: (])S'wi = 0.072% and k = 130 mD.
Chart Perm-2: c^S'™ = 0.072% and k = 65 mD.
2.0
1.6
Correction 1.4
factor, C
1.2
1.0
0.8
n ?nn
ILL Mr tuu
.«■"
,*
,/'
f
4 r
J
f
1
r
,r
" I n p,„ — p„ ' '
- : - - Pc JO
J
,i' "">« p c - IUU
•"" n 1(1
,1 . Pc lu .
— .-.,,,,,,,,,,,,,..— p _Q
20 40 60 80
Irreducible water saturation, S wi (%)
100
) Schlumberger
268
Back to Contents
Permeability
Permeability from Porosity and Water Saturation
Open Hole
Schlumberger
Perm-1
(former K-3)
60
50
40
Irreducible
water
saturation ,n
above
transition
zone,
s wi (%>
20
10
I
1
P
0.5
1
I
i
ft
/
p \l i r
/
1
0.1
In
m \
2
S w
/*
/
r
/
0.12
1(1
0.10
?n
V
l>
50
>
>rf
u.ua
00
*J
3
200
n n
4
" bl
JU
j±{
.
1,
300
s'
-^
5,uuu
^
.02
•^
01.
C
© Schlumberger
5 10 15 20 25 30 35 40
Porosity, <|> (p.u.)
< ►
Back to Contents
269
Permeability
Permeability from Porosity and Water Saturation
Open Hole
Schlumberger
Perm-2
(former K-4)
40
35
30
25
Porosity, 20
(j)(p.U.)
15
10
5
,ui
JU
,
/
1
,
2,000
/
■0
f\ /| /
V
\
V 1,000 j
%
f.
)
<|
dU
/
1
/
t
/
20
n
V
i"
/
/
■
1
oc
v if
)
Rfl
nnp
20
nr
6
A / J
/
5
04
n
n'
1
nni
n n
.
(
© Schlumberger
1
]
2(
)
Ir
3(
re
)
;ib
le
w
4
aft
]
>r ;
at
ur
at
5
on
]
a
30
je
m
6
n
.it
on
zc
>n
7
3,
5
(°/
»)
8
]
90
100
This chart is used similarly to Chart Perm-1 for the relation
k 1/2 70A 2
'l-S ^
o
V wi J
270
< ►
Back to Contents
Permeability
Schlumberger
Fluid Mobility Effect on Stoneley Slowness
Open Hole
Perm-3
10,000
Fresh Mud at 600 Hz
1,000
Mobility
(mD/cp) 10 n
10
0.1
|
1
1
lUlc
mbr
ane
im
in
c
pe
/
50
10/
5
\//
/ OGPa/cm
(no mudcake)
i
/
/
I
/
/
/
/
/
1
/
/
I
/
/
1
1
/
/
/
/
/
/
© Schlumberger
1 1 10 100
Mobility-added slowness, S - S e (u,s/ft)
Purpose
This chart is used to estimate ease of movement through a formation
by a fluid.
Description
The mobility-added slowness, which is the difference between the
Stoneley slowness and the calculated elastic Stoneley slowness, is
plotted on the x-axis and the mobility of the fluid is on the y-axis. The
membrane impedance curves represent the effect that the mudcake
has on the determination of the mobility of the fluid in the formation.
The membrane impedance is scaled in gigapascal per centimeter.
Back to Contents
271
Cement Evaluation — Wireline
Cement Bond Log — Casing Strength
Interpretation — Cased Hole
Schlumberger
Purpose
This chart is used to determine the decibel attenuation of casing
from the measured cement bond log (CBL) amplitude and convert
it to the compressive strength of bonded cement (either standard
or foamed).
Description
The amplitude of the first casing arrival is recorded by an acoustic
signal-measuring device such as a sonic or cement bond tool. This
amplitude value is a measure of decibel attenuation that can be
translated into a bond index (an indication of the percent of casing
cement bonding) and the compressive strength (psi) of the cement
at the time of logging.
Enter the chart on the y-axis with the log value of CBL amplitude
and move upward parallel to the 45° lines to intersect the appropri-
ate casing size. At that point, move horizontally right to the attenua-
tion scale on the right-hand y-axis. From this point, draw a line
through the appropriate casing thickness value to intersect the com-
pressive strength scale. The casing wall thickness is calculated by
subtracting the nominal inside diameter (ID) from the outside
diameter (OD) listed on the table for threaded nonupset casing
and dividing the difference by 2.
Example
Given: Log amplitude reading = 3.5 mV in zone of interest
and 1.0 mV in a well-bonded section (usually the lowest
millivolt value on the log), casing size = 7 in. at
29 lbm/ft, casing thickness = 0.41 in., and neat cement
(not foamed).
Find: Compressive strength and bond index of the cement at
the time of logging.
Answer: Enter the 3.5-mV reading on the left y-axis of Chart
Cem-1 and proceed to the 7-in. casing line.
Move horizontally to intersect the right-hand y-axis at
8.9 dB/ft.
Determine the casing thickness as (7 - 6.184)/2 = 0.816/2
= 0.41 in. Draw a line from 8.9 dB/ft through the 0.41-in.
casing thickness point to the compressive strength scale.
Cement compressive strength = 2,100 psi.
To find the bond index, determine the decibel attenuation of the
lowest recorded log value by entering 1.0 mV on the left-hand y-axis
and proceeding to the 7-in. casing line. Move horizontally to intersect
the right-hand y-axis at 12.3 dB/ft.
Divide the precisely determined decibel attenuation for the CBL
amplitude in the zone of interest by this value for the lowest millivolt
value: 8.9/12.3 = 72% bond index.
A 72% bond index means that 72% of the casing is bonded. This
is not a well-bonded zone because a value of 80% bonding over a 10-ft
interval is historically considered well bonded. Although the logging
scale is a linear millivolts scale, the decibel attenuation scale is loga-
rithmic. The millivolts log scale for the CBL value cannot rescaled
in percent of bonding. If it were, the apparent percent bonding
would be 65% because most bond log scales are from to 100 mV
reading from left to right, over 10 divisions of track 1, or conversely
100% to 0% cement bonding for mV = 100% bonding and
100 mV = 0% bonding.
272
Back to Contents
Cement Evaluation — Wireline
Schlumberger
Cement Bond Log — Casing Strength
Interpretation — Cased Hole
Threaded
Nonupset Casing
OD
(in.)
Weight
per ft*
(Ibm)
Nominal
ID
(in.)
Drift
Diameter*
(in.)
OD
(in.)
Weight
perft T
(Ibm)
Nominal
ID
(in.)
Drift
Diameter*
(in.)
OD
(in.)
Weight
per ft*
(Ibm)
Nominal
ID
(in.)
Drift
Diameter*
(in.)
4
11.60
3.428
3.303
7
17.00
20.00
22.00
23.00
24.00
26.00
28.00
29.00
30.00
32.00
35.00
38.00
40.00
6.538
6.456
6.398
6.366
6.336
6.276
6.214
6.184
6.154
6.094
6.004
5.920
5.836
6.413
6.331
6.273
6.241
6.211
6.151
6.089
6.059
6.029
5.969
5.879
5.795
5.711
10
33.00
9.384
9.228
4K
9.50
11.60
13.50
4.090
4.000
3.920
3.965
3.875
3.795
10%
32.75
40.00
40.50
45.00
45.50
48.00
51.00
54.00
55.50
10.192
10.054
10.050
9.960
9.950
9.902
9.850
9.784
9.760
10.036
9.898
9.894
9.804
9.794
9.746
9.694
9.628
9.604
4 3 /
16.00
4.082
3.957
5
11.50
13.00
15.00
17.70
18.00
21.00
4.560
4.494
4.408
4.300
4.276
4.154
4.435
4.369
4.283
4.175
4.151
4.029
11 3 /
38.00
42.00
47.00
54.00
60.00
11.150
11.084
11.000
10.880
10.772
10.994
10.928
10.844
10.724
10.616
5X
13.00
14.00
15.00
15.50
17.00
20.00
23.00
5.044
5.012
4.974
4.950
4.892
4.778
4.670
4.919
4.887
4.849
4.825
4.767
4.653
4.545
n
20.00
24.00
26.40
29.70
33.70
39.00
7.125
7.025
6.969
6.875
6.765
6.625
7.000
6.900
6.844
6.750
6.640
6.500
12
40.00
11.384
11.228
13
40.00
12.438
12.282
13 3 /
48.00
12.715
12.559
8%
24.00
28.00
32.00
36.00
38.00
40.00
43.00
44.00
49.00
8.097
8.017
7.921
7.825
7.775
7.725
7.651
7.625
7.511
7.972
7.892
7.796
7.700
7.650
7.600
7.526
7.500
7.386
5 3 /
14.00
17.00
19.50
22.50
5.290
5.190
5.090
4.990
5.165
5.065
4.965
4.865
16
55.00
15.375
15.187
18 5 /
78.00
17.855
17.667
20
90.00
19.190
19.002
6
15.00
16.00
18.00
20.00
23.00
5.524
5.500
5.424
5.352
5.240
5.399
5.375
5.299
5.227
5.115
21 %
92.50
103.00
114.00
20.710
20.610
20.510
20.522
20.422
20.322
9
34.00
38.00
40.00
45.00
55.00
8.290
8.196
8.150
8.032
7.812
8.165
8.071
8.025
7.907
7.687
2VA
100.50
113.00
23.750
23.650
23.562
23.462
6%
17.00
20.00
22.00
24.00
26.00
26.80
28.00
29.00
32.00
6.135
6.049
5.989
5.921
5.855
5.837
5.791
5.761
5.675
6.010
5.924
5.864
5.796
5.730
5.712
5.666
5.636
5.550
t Weight per foot in pounds is given for plain pipe (no threads
or coupling)
t Drift diameter is the guaranteed minimum inside diameter of
5%
29.30
32.30
36.00
40.00
43.50
47.00
53.50
9.063
9.001
8.921
8.835
8.755
8.681
8.535
8.907
8.845
8.765
8.679
8.599
8.525
8.379
any part of the casing. Use drift diameter to determine the
largest-diameter equipment that can be safely run inside the
casing. Use inside diameter for volume capacity calculations.
< ►
Back to Contents
continued on next page
273
Cement Evaluation — Wireline
Cement Bond Log — Casing Strength
Interpretation — Cased Hole
Schlumberger
Cem-1
(former M-1)
1
70
50
40
30
20
15
10
9
8
7
6
5
CRI amplitndp ^
i/
5
Casi
10
V
ng
IS
6
size
)4
2"
m
3
3'
■0
Centered tool only, 3-ft [0.91 4-m] spacing
Attenuation
y
/
1 ' Compressive strength
_ 1 , {p f,
/
I (m
ra)
/
/
2
30
_ 4,000
25
3,000
= — 20
15
_ 2,000
10
- 1,000 Standard
cement
5
_ 500
3
2
R
3
/
1?
4
c 16
5
—/.
<<
5 20 Casing thickness
A
//
/
y A
'
(mm) (in.)
7 15 ^° 6
//
/
24 V
Tt- ° 5 Tjoa^S^^^l
/
'
28 ^-^^T H4
/l
i-
/
— ►<
**^~^™\
//
/
- 32 b __V
/ <
10 \_0 3
(mV) 3
2
1
0.5
0.2
4'
© Schlumberger
7 — t 1,000 I
11- 36 V_
/
/
12 .„ r snn
5 J- 0.2
13 c
44
14
4 _
48
MM)
" 250
1
_ 100
05
Foamed cement
ic- 52 3 —
IB
17 56 qnn
/
/
2 _
18
_ 50
0.3
V
h
5'
h
Cas
nc
1C
h
size
13
(in
3 /b
)
(dB/ft) 200
1 _
100
274
< ►
Back to Contents
Appendix A
Linear Grid
< ► Back to Contents
275
Appendix A
Log-Linear Grid
7 _ :
4 ===========================================================
3 ZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZ
2 EEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEE
5 El
4 EE:
3 zzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzz
2 EEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEE
276
-* ►
Back to Contents
Appendix A
Water Saturation Grid for Resistivity Versus Porosity
For F R :
0.62
5,000
4,000
3,000
2,500
2,000
Conductivity
(mmho/m)
1,500
1,000
500
400
300
200
150
100
50
25
10
Res
mul
in a
stivit
tipliet
highe
/sea
by 1
r ran
e ma
3 for i
/ bo
jse
0.20
0.25
0.30
0.35
0.40
0.45
0.50
0.60
0.70
0.80
Resistivity
0.90 (ohm-m)
1.0
1.2
1.4
1.6
1.8
2.0
2.5
3.0
4.0
5.0
6.0
8.0
10
15
20
30
40
50
100
200
JPb
F„
Back to Contents
277
Appendix A
Water Saturation Grid for Resistivity Versus Porosity
ForF„
500
400
300
250
200
150
Conductivity
(mmho/m)
100
50
40
30
20
10
Res
stivity scale may be
mull
in a
ipliec
night
uy i
r ran
j Tor i
ge
se
2.5
3.5
4
4.5
5
o Resistivity
(ohm-m)
9
10
12
14
16
20
25
30
40
50
100
200
500
1,000
2,000
JPb
278
< ►
Back to Contents
Appendix B
Logging Tool Response in Sedimentary Minerals
Name
Formula
Plug
(g/cm 3 )
^SNP
(p.u.)
»CNL
(p.u.)
9APS 1
(p.u.)
Ate
(fis/ft)
At,
(US/ft)
Pe
8
(farad/m)
tp
(ns/m)
Gamma Ray
(gAPI Units)
(c.u.)
Silicates
Quartz
Si0 2
2.64
-1
-2
-1
56.0
88.0
1.8
4.8
4.65
7.2
4.3
(i-cristobalite
Si0 2
2.15
-2
-3
1.8
3.9
3.5
Opal (3.5% H 2 0)
Si0 2 (H 2 0)o.1209
2.13
4
2
58
1.8
3.7
5.0
Garnet'
Fe 3 AI 2 (Si0 4 )3
4.31
3
7
11
48
45
Hornblende*
Ca 2 NaMg 2 Fe 2
AISi B 22 (0,OH) 2
3.20
4
8
43.8
81.5
6.0
19
18
Tourmaline
NaMg 3 AI 6 B3Si 6 2 (OH|4
3.02
16
22
2.1
6.5
7450
Zircon
ZrSi0 4
4.50
-1
-3
69
311
6.9
Carbonates
Calcite
CaC0 3
2.71
49.0
88.4
5.1
13.8
7.5
9.1
7.1
Dolomite
CaC0 3 MgC0 3
2.85
2
1
1
44.0
72
3.1
9.0
6.8
8.7
4.7
Ankerite
Ca(Mg,Fe)(C0 3 ) 2
2.86
1
9.3
27
22
Siderite
FeC0 3
3.89
5
12
3
47
15
57
6.8-7.5
8.8-9.1
52
Oxidates
Hematite
Fe 2 3
5.18
4
11
42.9
79.3
21
111
101
Magnetite
Fe 3 4
5.08
3
9
73
22
113
103
Goethite
FeO(OH)
4.34
50+
60+
19
83
85
Limonite*
FeO(OH)(H 2 OKos
3.59
50+
60+
56.9
102.6
13
47
9.9-10.9
10.5-11.0
71
Gibbsite
AI(OH) 3
2.49
50+
60+
1.1
23
Phosphates
Hydroxyapatite
Ca 5 (P0 4 ) 3 OH
3.17
5
8
42
5.8
18
9.6
Chlorapatite
Ca 5 (P0 4 | 3 CI
3.18
-1
-1
42
6.1
19
130
Fluorapatite
Ca 5 (P0 4 |3F
3.21
-1
-2
42
5.8
19
8.5
Carbonapatite
(Ca 5 (P0 4 ) 3 )2C0 3 H 2
3.13
5
8
5.6
17
9.1
Feldspars — Alkali*
Orthoclase
KAISbOa
2.52
-2
-3
69
2.9
7.2
4.4-6.0
7.0-8.2
-220
16
Anorthoclase
KAISbOa
2.59
-2
-2
2.9
7.4
4.4-6.0
7.0-8.2
-220
16
Microcline
KAISi 3 B
2.53
-2
-3
2.9
7.2
4.4-6.0
7.0-8.2
-220
16
Feldspars — Plagioclase*
Albite
NaAISbOa
2.59
-1
-2
-2
49
85
1.7
4.4
4.4-6.0
7.0-8.2
7.5
Anorthite
CaAI 2 Si 2 O a
2.74
-1
-2
45
3.1
8.6
4.4-6.0
7.0-8.2
7.2
Micas*
Muscovite
KAI 2 (SbAIO, }(OH| 2
2.82
12
-20
-13
49
149
2.4
6.7
6.2-7.9
8.3-9.4
-270
17
Glauconite
Ko.7(Mg,Fe 2 ,AD
(Si 4 ,Aho)0 2 (OH)
2.86
-38
-15
4.8
14
21
Biotite
K(Mg,Fe) 3 (AISi 3 O, )(OH) 2
-2.99
-11
-21
-11
50.8
224
6.3
19
4.8-6.0
7.2-8.1
-275
30
Phlogopite
KMg 3 (AISi 3 Oio)(OH) 2
50
207
33
•APS* Accelerator Porosity Sonde porosity derived from near-to-array ratio (APLCI
•Mean value, which may vary for individual samples
For more information, see Reference 41.
Back to Contents
279
Appendix B
Logging Tool Response in Sedimentary Minerals
Name
Formula
Plog
(g/cm 3 )
9SNP
(p.u.)
OCNL
(p.u.)
9APS 1
(p.u.)
Ate
(ps/ft)
At,
(US/ft)
Pe
8
(farad/m)
(ns/m)
Gamma Ray
(gAPI Units)
(c.u.)
Clays*
Kaolinite
AUSi 4 Oio(OH) 8
2.41
34
-37
-34
1.8
4.4
-5.8
-8.0
80-130
14
Chlorite
(Mg,Fe,AI) 6 (Si,AI) 4
0,o(OH) a
2.76
37
-52
-35
6.3
17
-5.8
-8.0
180-250
25
lllite
Kl-1.5Al4(Si7-6.5,All-1.5)
□2o(OH) 4
2.52
20
-30
-17
3.5
8.7
-5.8
-8.0
250-300
18
Montmorillonite
(Ca,Na) 7 (AI,Mg,Fe) 4
(Si,AI) a 02o(OH)4(H 2 0)„
2.12
-60
-60
2.0
4.0
-5.8
-8.0
150-200
14
Eva po rites
Halite
NaCI
2.04
-2
-3
21
67.0
120
4.7
9.5
5.6-6.3
7.9-8.4
754
Anhydrite
CaS0 4
2.98
-1
-2
2
50
5.1
15
6.3
8.4
12
Gypsum
CaS0 4 (H 2 0) 2
2.35
50+
60+
60
52
4.0
9.4
4.1
6.8
19
Trona
Na 2 C03NaHCQ3H 2
2.08
24
35
65
0.71
1.5
16
Tachhydrite
CaCI 2 (MgCI 2 | 2 (H 2 0), 2
1.66
50+
60+
92
3.8
6.4
406
Sylvite
KCI
1.86
-2
-3
8.5
16
4.6-4.8
7.2-7.3
500+
565
Carnalite
KCIMgCl 2 (H 2 0| 6
1.57
41
60+
4.1
6.4
-220
369
Langbeinite
K 2 S0 4 (MgS0 4 ) 2
2.82
-1
-2
3.6
10
-290
24
Polyhalite
K 2 S0 4 Mg
S0 4 (CaS0 4 ) 2 (H 2 0) 2
2.79
14
25
4.3
12
-200
24
Kainite
MgS0 4 KCI(H 2 0) 3
2.12
40
60+
3.5
7.4
-245
195
Kieserite
MgS0 4 (H 2 0)
2.59
38
43
1.8
4.7
14
Epsomite
MgS0 4 (H 2 0) 7
1.71
50+
60+
1.2
2.0
21
Bischofite
MgCI 2 (H 2 0} 6
1.54
50+
60+
100
2.6
4.0
323
B a rite
BaS0 4
4.09
-1
-2
267
1090
6.8
Celestite
SrS0 4
3.79
-1
-1
55
209
7.9
Sulfides
Pyrite
FeS 2
4.99
-2
-3
39.2
62.1
17
85
90
Marcasite
FeS 2
4.87
-2
-3
17
83
88
Pyrrhotite
Fe 7 S 8
4.53
-2
-3
21
93
94
Sphalerite
ZnS
3.85
-3
-3
36
138
7.8-8.1
9.3-9.5
25
Chalcopyrite
CuFeS 2
4.07
-2
-3
27
109
102
Galena
PbS
6.39
-3
-3
1,630
10,400
13
Sulfur
S
2.02
-2
-3
122
5.4
11
20
Coals
Anthracite
CHo.35bNd.OQ90o.022
1.47
37
38
105
0.16
0.23
8.7
Bituminous
CH0.793N0.015O0.07B
1.24
50+
60+
120
0.17
0.21
14
Lignite
CH0.BwN0.015O0.211
1.19
47
52
160
0.20
0.24
13
f APS* Accelerator Porosity Sonde porosity derived from near-to-array ratio (APLCI
•Mean value, which may vary for individual samples
For more information, see Reference 41.
280
Back to Contents
Appendix C
Acoustic Characteristics of Common Formations and Fluids
Anhydrite
Limestone
Calcite
50.0
47.6
49.7
Nonporous Solids
Material
At
(Us/ft)
Sound Velocity
Acoustic Impedance
(ft/s)
(m/s)
(MRayl)
Casing
57.0
17,500
5,334
41.60
Dolomite
43.5
23,000
7,010
20.19
20,000
6,096
18.17
21,000
6,400
17.34
20,100
6,126
16.60
Quartz
Gypsum
52.9
52.6
18,900
19,000
5,760
5,791
15.21
13.61
Halite
66.6
15,000
4,572
9.33
Kerosene
Airat15psi,32°F[0°C]
Air at 3,000 psi,212°F[100°C]
Water-Saturated Porous Rock
Material
Porosity
(%)
At
(ps/ft)
Sound Velocity
Acoustic Impedance
(ft/s)
(m/s)
(MRayl)
Dolomite
5-20
50.0-66.6
20,000-15,000
6,096^,572
16.95-11.52
Limestone
5-20
54.0-76.9
18,500-13,000
5,639-3,962
14.83-9.43
Sandstone
5-20
62.5-86.9
16,000-11,500
4,877-3,505
12.58-8.20
Sand
20-35
86.9-111.1
11,500-9,000
3,505-2,743
8.20-6.0
Shale
58.8-143.0
17,000-7,000
5,181-2,133
12.0-4.3
Nonporous Solids
Material
At
(ps/ft)
Sound Velocity
Acoustic Impedance
(ft/s)
(m/s)
(MRayl)
Water
208
4,800
1,463
1.46
Water + 10% NaCI
192.3
5,200
1,585
1.66
Water + 20% NaCI
181.8
5,500
1,676
1.84
Seawater
199
5,020
1,531
1.57
230
920
780
4,340
1,324
1,088
331
1,280
390
1.07
0.0004
0.1
Back to Contents
281
Appendix D
Conversions
Length
\^ Multiply
>v Number
\ of
to \^
Obtain by
Centimeters
Feet
Inches
Kilometers
Nautical
Miles
Meters
Mils
Miles
Millimeters
Yards
Centimeters
1
30.48
2.540
10=
1.853x10=
100
2.540 x10- 3
1.609x10=
0.1
91.44
Feet
3.281 x10 2
1
8.333 x10 2
3281
6080.27
3.281
8.333x10-=
5280
3.281 x10 3
3
Inches
0.3937
12
1
3.937x10'
7.296x10"
39.37
0.001
6.336x10"
3.937 x10 2
36
Kilometers
10-=
3.048x10-"
2.540x10-=
1
1.853
0.001
2.540x10-"
1.609
10-=
9.144x10-"
Nautical miles
1.645x10-"
0.5396
1
5.396x10"
0.8684
4.934x10"
Meters
0.01
0.3048
2.540 x10- 2
1000
1853
1
1609
0.001
0.9144
Mils
393.7
1.2x 10"
1000
3.937x10'
3.937x10"
1
39.37
3.6x10"
Miles
6.214X 10 6
1.894x10-"
1.578X10 5
0.6214
1.1516
6.214x10-"
1
6.214X10 7
5.682x10-"
Millimeters
10
304.8
25.40
10=
1000
2.540 x10- 2
1
914.4
Yards
1.094 x10 2
0.3333
2.778 x10 2
1094
2027
1.094
2.778x10 =
1760
1.094x10"
1
Area
^^ Multiply
^\ Number
\ of
to >^
Obtain (,y
Acres
Circular
Mils
Square
Centimeters
Square
Feet
Square
Inches
Square
Kilometers
Square
Meters
Square
Miles
Square
Millimeters
Square
Yards
Acres
1
2.296x10 =
247.1
2.471 x10-"
640
2.066x10"
Circular mils
1
1.973x10=
1.833x10"
1.273x10"
1.973x10"
1973
Square
centimeters
5.067X10 6
1
929.0
6.452
10'"
10"
2.590 x10 10
0.01
8361
Square feet
4.356x10"
1.076X10 3
1
6.944x10-"
1.076x10'
10.76
2.788x10'
1.076x10 =
9
Square inches
6,272,640
7.854x10'
0.1550
144
1
1.550x10"
1550
4.015x10"
1.550x10"
1296
Square
kilometers
4.047x10"
10-'°
9.290x10-"
6.452 x10- ,D
1
10-"
2.590
10-' 2
8.361 X10-'
Square meters
4047
0.0001
9.290X10- 2
6.452x10-"
10"
1
2.590x10"
10-"
0.8361
Square miles
1.562X10 3
3.861 X10-"
3.587x10"
0.3861
3.861 X10-'
1
3.861 x10-'"
3.228x10-'
Square
millimeters
5.067x10-"
100
9.290x10"
645.2
10 12
10"
1
8.361 x10=
Square yards
4840
1.196x10-"
0.1111
7.716x10-"
1.196x10"
1.196
3.098x10"
1.196x10"
1
282
Back to Contents
Appendix D
Conversions
Volume
N. Multiply
\ Number
\ of
to \a
Obtain D y
Bushels
(Dry)
Cubic
Centimeters
Cubic
Feet
Cubic
Inches
Cubic
Meters
Cubic
Yards
Gallons
(Liquid)
Liters
Pints
(Liquid)
Quarts
(Liquid)
Bushels (dry)
1
0.8036
4.651 x10- 4
28.38
2.838 x10- 2
Cubic
centimeters
3.524 x10"
1
2.832X 10 4
16.39
10 E
7.646x10=
3785
1000
473.2
946.4
Cubic feet
1.2445
3.531 xirr 5
1
5.787x10-"
35.31
27
0.1337
3.531 x10 2
1.671 x10 2
3.342 x10 2
Cubic inches
2150.4
6.102 xirr 2
1728
1
6.102x10"
46,656
231
61.02
28.87
57.75
Cubic meters
3.524 x1fr 2
10^
2.832 x10 2
1.639x10-=
1
0.7646
3.785 X10 3
0.001
4.732x10-"
9.464x10-"
Cubic yards
1.308x10 =
3.704 x10- 2
2.143x10 =
1.308
1
4.951 x10 3
1.308 x10 3
6.189 x 10-"
1.238 x10 3
Gallons
(liquid)
2.642 x 10-"
7.481
4.329 xlO 3
264.2
202.0
1
0.2642
0.125
0.25
Liters
35.24
0.001
28.32
1.639 x10 2
1000
764.6
3.785
1
0.4732
0.9464
Pints (liquid)
2.113 x 10 3
59.84
3.463 x10 2
2113
1616
8
2.113
1
2
Quarts (liquid)
1.057 x10- 3
29.92
1.732 x10- 2
1057
807.9
4
1.057
0.5
1
Mass and Weight
^v Multiply
^\ Number
\ of
to \^
Obtain by
Grains
Grams
Kilograms
Milligrams
Ounces'
Pounds'
Tons
(Long)
Tons
(Metric)
Tons
(Short)
Grains
1
15.43
1.543x10"
1.543 x10 2
437.5
7000
Grams
6.481 x10- 2
1
1000
0.001
28.35
453.6
1.016x10=
10=
9.072x10=
Kilograms
6.481 x10-=
0.001
1
10-=
2.835 x10- 2
0.4536
1016
1000
907.2
Milligrams
64.81
1000
10=
1
2.835x10"
4.536x10=
1.016x10 s
10 9
9.072x10"
Ounces'
2.286 x10- 3
3.527 x10 2
35.27
3.527x10 =
1
16
3.584x10"
3.527x10"
3.2x10"
Pounds'
1.429x10-"
2.205 X10 3
2.205
2.205x10 =
6.250 x10- 2
1
2240
2205
2000
Tons (long)
9.842x10-'
9.842x10-"
9.842 x10-'»
2.790x10 =
4.464x10-"
1
0.9842
0.8929
Tons (metric)
io-=
0.001
10-=
2.835x10-=
4.536x10-"
1.016
1
0.9072
Tons (short)
1.102x10-=
1.102 x TO 3
1.102 x 10 9
3.125x10 =
0.0005
1.120
1.102
1
'Avoirdupois pounds and ounces
Back to Contents
283
Appendix D
Conversions
Pressure or Force per Unit Area
\ Multiply
\ Number
\ of
to \^
Obtain "^ by
Atmospheres*
Bayres or
Dynes per
Square
Centimeter*
Centimeters
of Mercury
at 0°C S
Inches
of Mercury
at 0°C S
Inches
of Water
at4°C
Kilograms
per
Square
Meter"
Pounds
per
Square Foot
Pounds
per
Square
Inch**
Tons (short)
per
Square Foot
Pascals
Atmospheres*
1
9.869x10-'
1.316 x10- 2
3.342 x10- 2
2.458 x10- 3
9.678x10-=
4.725x10-*
6.804 x10- 2
0.9450
9.869x10-=
Bayres or dynes
per square
centimeter*
1.013X 10 6
1
1.333x10*
3.386x10*
2.491 x10 3
98.07
478.8
6.895x10*
9.576x10=
10
Centimeters
of mercury
atO°C s
76.00
7.501 x10 5
1
2.540
0.1868
7.356 x10- 3
3.591 x10 2
5.171
71.83
7.501 X10-*
Inches
of mercury
atO°C s
29.92
2.953x10-=
0.3937
1
7.355 x10 2
2.896 x10- 3
1.414 x10- 2
2.036
28.28
2.953x10-*
Inches of
water at 4°C
406.8
4.015x10-*
5.354
13.60
1
3.937 x10 2
0.1922
27.68
384.5
4.015 x10 3
Kilograms
per square
meter'*
1.033x10*
1.020 x10- 2
136.0
345.3
25.40
1
4.882
703.1
9765
0.1020
Pounds
per square
foot
2117
2.089 x10- 3
27.85
70.73
5.204
0.2048
1
144
2000
2.089 x10- 2
Pounds per
square inchM
14.70
1.450x10 =
0.1934
0.4912
3.613 x10 2
1.422 x10 3
6.944 x10- 3
1
13.89
1.450x10-*
Tons (short) per
square foot
1.058
1.044x10 =
1.392 x10 2
3.536 x10- 2
2.601 X10 3
1.024x10-*
0.0005
0.072
1
1.044x10 =
Pascals
1.013x10=
io-'
1.333 x10 3
3.386 x10 3
2.491 X10-*
9.807
47.88
6.895 x10 3
9.576x10*
1
* One atmosphere (standard) = 76 cm of mercury at 0°C
* Bar
s To convert height/; of a column of mercury at f°C to the equivalent height ht at 0°C, use h a = h[\ -[(m-l) f/1 +m!j} : where m = 0.0001 81 8 and /= 18.4 x 10 6 if the
scale is engraved on brass; /=8.5 x TO 6 if on glass. This assumes the scale is correct at 0°C; for other cases (any liquid) see International Critical Tables,Vo\. 1,68.
** 1 gram per square centimeter = 10 kilograms per square meter
** psi = MPax 145.038
psi/ft = 0.433 x g/cm 3 = Ibf/ft7l44 = lbf/gal/1 9.27
Density or Mass per Unit Volume
^^^^ Multiply
^^^ Number
\ of
Obtain ^^ D y
Grams per
Cubic
Centimeter
Kilograms
per
Cubic Meter
Pounds per
Cubic Foot
Pounds per
Cubic Inch
Pounds per
Gallon
Grams per cubic centimeter
1
0.001
1.602 x10 2
27.68
0.1198
Kilograms per cubic meter
1000
1
16.02
2.768x10"
119.8
Pounds per cubic foot
62.43
6.243 x10- 2
1
1728
7.479
Pounds per cubic inch
3.613 x10 2
3.613x10-=
5.787x10*
1
4.329 X10 3
Pounds per gallon
8.347
8.3 x10 3
13.37x10 2
231.0
1
Temperature
°F
1.8°C
+ 32
°C
%{°F
-32)
°R
°F + 459.69
K
°C +
'73.16
284
Back to Contents
Appendix E
Symbols
Traditional
Standard
Standard
Symbol
SPE
and
SPWLA f
Computer
Symbol 1
Description
Customary Unit or Relation
L
M
L
M
LTH
SAD
MXP
length, path length
slope, sonic interval transit time versus
density x 0.01, in M-N plot
porosity (cementation) exponent
ft, m, in.
M = [(X f -X LOG )/(p b -p f )]x0.01
Fr = KrAT
Standard
Reserve
Symbol*
a
a
ACT
electrochemical activity
equivalents/liter, moles/liter
a
Kr
COER
coefficient in F R -<t> relation
Fr = K R /<T
M R , a, C
A
A
AWT
atomic weight
amu
C
C
ECN
conductivity (electrical logging)
millimho per meter
mmho/m)
a
C P
E>cp
CORCP
sonic compaction correction factor
< t ) SVcor = Bcp't'SV
^cp
D
D
DPH
depth
ft, m
y,H
d
d
DIA
diameter
in.
D
E
E
EMF
electromotive force
mV
V
F
Fr
FACHR
formation resistivity factor
Fr = K R /r
G
G
GMF
geometrical factor (multiplier)
f G
H
Ih
HYX
hydrogen index
in
h
h
THK
bed thickness, individual
ft, m, in.
d,e
1
-X
index
i
FFI
'ft
FFX
free fluid index
ir-i
SI
'si
SLX
silt index
'sit- isl> 'sit
'♦
PRX
porosity index
i«
SPI
U2
PRXSE
secondary porosity index
i 2
J
G P
GMFP
pseudogeometrical factor
fsp
K
Kc
COEC
electrochemical SP coefficient
E c = K c log(a w /a mf )
M c ,K ec
k
k
PRM
permeability, absolute (fluid flow)
mD
K
s,t
"BD
N
N
SND
slope, neutron porosity
density, in M-N Plot
versus
N = ((fNf-<t ) N)/(P[
n
n
SXP
saturation exponent
S w n = pRR w /Rt
P
C
CNC
salinity
g/g. ppm
P
P
PRS
pressure
psi, kg/cm 2 , § atm
Pc
Pc
PRSCP
capillary pressure
psi, kg/cm 2 , § atm
>>ND
c, n
Pe
photoelectric cross section
P
Pc Pc
' SPE Letter and Computer Symbols Standard (1986).
* Used only if conflict arises between standard symbols used in the same paper
§ The unit of kilograms per square centimeter to be replaced in use by the SI metric unit of the pascal
tr "DEL" in the operator field and "RAD" in the main-quantity field
K Suggested computer symbol
Back to Contents
285
Appendix E
Symbols
Traditional
Standard
Standard
Symbol
SPE
and
SPWLA f
Computer
Symbol 1
Description
Customary Unit or Relation
BHT,T bh
FT,T fm
T
Tbh
T,
TEM temperature
TEMBH bottomhole temperature
TEMF formation temperature
3 F, °C, K
3 F, °C, K
3 F, °C, K
Standard
Reserve
Symbol*
Qv
shaliness (CEC per mL water)
meq/mL
q
f<|>shd
FIMSHD
dispersed-shale volume fraction of
intermatrix porosity
timfshd-l
R
R
RES
resistivity (electrical)
ohm-m
P.r
r
r
RAD
radial distance from hole axis
in.
R
S
S
SAT
saturation
fraction or percent
of pore volume
p,s
■>BH
I
t
u
TIM
TAC
time
interval transit time
volumetric cross section
u.s, s, mm
barns/cm 3
t
At
v
V
V
VAC
VOL
VLF
velocity (acoustic)
volume
volume fraction
ft/s, m/s
cm 3 , ft 3 , etc.
V, u
v
fv,F w
Z
a
1
Z ANM atomic number
oc SP REDSP SP reduction factor
Y SPG specific gravity (p/p m or p g /p air
s, F s
<t>2
T dN
POR porosity
PORPR primary porosity
PORSE secondary porosity
fraction or percentage
of bulk volume, p.u.
fraction or percentage
of bulk volume, p.u.
fraction or percentage
of bulk volume, p.u.
XST neutron capture cross section
XSTMAC macroscopic
TIMDN thermal neutron decay time
c.u., crrr
LIS
f,e
fi-e.
f*e 2
4>ig
PORIG
intergranular porosity
4>ig = (V b -
-v gr )/v b
Mg- E ig
<t>z- <t>im
<t>im
PORIM
intermatrix porosity
<t>im = (Vb
-v ma )/v b
Mm' e im
Ar
Ar
DELRAD"
radial distance (increment)
in.
AR
At
1
TAC
sonic interval transit time
U-S/ft
At
^Hex
DELPORNX"
excavation effect
p.u.
X
^ani
COEANI
coefficient of anisotropy
Mani
P
P
DEN
density
g/cm 3
D
S
t-dn
' SPE Letter and Computer Symbols Standard{1986).
* Used only if conflict arises between standard symbols used in the same paper
§ The unit of kilograms per square centimeter is to be replaced in use by the SI metric unit of the pascal.
Tt "DEL" in the operator field and "RAD" in the main-quantity field
K Suggested computer symbol
286
Back to Contents
Appendix F
Subscripts
Traditional
Standard
Standard
Subscript
SPE
and
SPWLA f
Computer
Subscript*
Explanation
Example
g, gas
gxo
9
gr
gxo
GR
GXO
gas
gram
gas in flushed zone
J gxo
Standard
Reserve
Subscript*
a
LOG
L
apparent from log reading
(or use tool description subscript)
R|_OG'
Rll
log
a
a
A
apparent (general)
Ra
ap
abs
cap
C
absorption, capture
■^■cap
anh
anh
AH
anhydrite
b
b
B
bulk
Pb
B,t
bh
bh
BH
bottomhole
Tbh
w, BH
clay
cl
CL
clay
V C |
cla
cor, c
cor
COR
corrected
tcor
c
c
C
electrochemical
Ec
ec
cp
cp
CP
compaction
B cp
D
D
D
density log
d
dis
shd
SHD
dispersed shale
Mshd
dol
dol
DL
dolomite
tdol
e, eq
eq
EV
equivalent
"waqi
"mfaq
EV
f, fluid
f
F
fluid
Pf
fl
fm
f
F
formation (rock)
T f
fm
GXO
gyp
gyp
GY
gypsum
Pgyp
h
h
H
hole
d h
H
h
h
H
hydrocarbon
Ph
H
hr
hr
HR
residual hydrocarbon
Shr
i
i
1
invaded zone (inner boundary)
di
1
ig
ig
IG
intergranular (incl. disp. and str. shale)
*i£l
im, z
im
IM
intermatrix (incl. disp. shale)
<t>im
int
int
1
intrinsic (as opposed to log value)
E int
irr
i
IR
irreducible
Syvi
ir, i
J
J
J
liquid junction
E i
(
k
k
K
electro kinetic
E k
ek
1
L
log
*Pi
log
lam
f
LAM
lamination, laminated
V sn f
L
lim
lim
LM
limiting value
<t>lim
liq
L
L
liquid
PL
('
SPE Letter and Computer Symbols Standard (1986).
Used only if conflict arises between standard symbols used in the same paper
< ►
Back to Contents
287
Appendix F
Subscripts
Traditional
Standard
Standard
Subscript
SPE
and
SPWLA f
Computer
Subscript*
Explanation
Example
Standard
Reserve
Subscript*
log
LOG
L
log values
t|_0G
log
Is
Is
LS
limestone
tls
1st
m
m
M
mud
Rm
max
max
MX
maximum
9 max
ma
ma
MA
matrix
Mna
mc
mc
MC
mudcake
"mc
mf
mf
MF
mud filtrate
R mf
mfa
mfa
MFA
mud filtrate, apparent
Rmfa
min
min
MN
minimum value
ni
noninvaded zone
R ni
oil (except with resistivity)
So
N
or
or
OR
residual oil
^or
o,0 (zero)
O(zero)
ZR
100-percent water saturated
Fo
zr
P
propagation
tpw
PSP
pSP
PSP
pseudostatic SP
Epsp
pri
1 (one)
PR
primary
♦ l
p,pri
r
r
R
relative
Kro< ^rw
R
r
r
R
residual
^or> ^hr
R
s
s
S
adjacent (surrounding) formation
R s
sd
sd
SD
sand
sa
ss
ss
SS
sandstone
sst
sec
2
SE
secondary
<t>2
s, sec
sh
sh
SH
shale
Vsh
sha
silt
si
SL
silt
1.1
sit
SP
SP
SP
spontaneous potential
Esp
sp
SSP
SSP
SSP
static spontaneous potential
Essp
str
sh st
SHST
structural shale
Mihst
s
t, ni
t
T
true (as opposed to apparent)
Rt
tr
T
t
T
total
c,
T
w
w
W
water, formation water
^w
W
wa
wa
WA
formation water, apparent
"wa
Wap
wf
wf
WF
well flowing conditions
Pwf
f
ws
ws
WS
well static conditions
Pws
s
xo
xo
XO
flushed zone
R xo
z, im
im
IM
intermatrix
*lm
SPE Letter and Computer Symbols Standardises).
Used only if conflict arises between standard symbols used in the same paper
288
Back to Contents
Appendix F
Subscripts
Traditional
Standard
Standard
Subscript
SPE
and
SPWLA 1
Computer
Subscript 1 '
Explanation
Example
Standard
Reserve
Subscript*
(zero)
O(zero)
ZR
100 percent water saturated
Ro
zr
AD
RAD
from CDR attenuation deep
Rad
D
D
D
from density log
4>D
d
GG
GG
from gamma-gamma log
<t>GG
gg
IL
I
I
from induction log
Ri
i
ILD
ID
ID
from deep induction log
R|D
id
ILM
IM
IM
from medium induction log
R|M
im
LL
LL(alsoLL3,
LL8, etc.)
LL
from laterolog
(also LL3, LL7, LL8, LLD, LLS)
Rll
('('
N
N
N
from normal resistivity log
Rn
n
N
N
N
from neutron log
<t>N
n
PS
RPS
from CDR phase-shift shallow
Rps
16", 16"N
from 16-in. normal Log
Rl6"
1"x 1"
from 1 -in. by 1-in. microinverse (Ml)
Ri"xi"
2"
from 2-in. micronormal (MN)
R 2 .
SPE Letter and Computer Symbols Standard (1986).
Used only if conflict arises between standard symbols used in the same paper
Back to Contents
289
Appendix G
Unit Abbreviations
These unit abbreviations, which are based on those adopted by the
Society of Petroleum Engineers (SPE), are appropriate for most publi-
cations. However, an accepted industry standard may be used instead.
For instance, in the drilling field, ppg may be more common than
lbm/gal when referring to pounds per gallon
In some instances, two abbreviations are given: customary and
metric. When using the International System of Units (SI), or metric,
abbreviations, use the one designated for metric (e.g., m 3 /h instead of
mVhr). The use of SI prefix symbols and prefix names with customaiy
unit abbreviations and names, although common, is not preferred
(e.g., 1,000 lbf instead of klbf).
Unit abbreviations are followed by a period only when the abbrevia-
tion forms a word (for example, in. for inch).
acre Spell out
acre-foot acre-ft
ampere A
ampere-hour A-hr
angstrom unit (10~ 8 cm) A
atmosphere atm
atomic mass unit amu
barrel bbl
barrels of fluid per day BFPD
barrels of liquid per day BLPD
barrels of oil per day BOPD
barrels of water per day BWPD
barrels per day B/D
barrels per minute bbl/min
billion cubic feet (billion = 10 9 ) Bcf
billion cubic feet per day Bcf/D
billion standard cubic feet per day Use Bcf7D instead of Bscf/D
(see "standard cubic foot")
bits per inch bpi
bits per second bps
brake horsepower bhp
British thermal unit Btu
capture unit c.u.
centimeter cm
centipoise cp
centistoke cSt
coulomb C
counts per second cps
cubic centimeter cm 3
cubic foot ft 3
cubic feet per barrel ft 3 /bbl
cubic feet per day ft 3 /D
cubic feet per minute ft 3 /min
cubic feet per pound ft/Vlbm
cubic feet per second ft 3 /s
cubic inch in. 3
cubic meter m 3
cubic millimeter mm 3
cubic yard yd 3
290
a ► Back
curie Ci
dalton Da
darcy, darcies D
day (customary) D
day (metric) d
dead-weight ton DWT
decibel dB
degree (American Petroleum Institute) "API
degree Celsius °C
degree Fahrenheit °F
degree Kelvin See "kelvin"
degree Rankine °R
dots per inch dpi
electromotive force emf
electron volt eV
farad F
feet per minute ft/min
feet per second ft/s
foot ft
foot-pound ft-lbf
gallon gal
gallons per day gal/D
gallons per minute gal/min
gigabyte Gbyte
gigahertz GHz
gigapascal GPa
gigawatt GW
gram g
hertz Hz
horsepower hp
horsepower-hour hp-hr
hour (customary) hr
hour (metric) h
hydraulic horsepower hhp
inch in.
inches per second in./s
joule J
kelvin K
kilobyte kB
kilogram kg
kilogram-meter kg-m
kilohertz kHz
kilojoule kJ
kilometer km
kilopascal kPa
kilopound (force) (1,000 lbf) klbf
kilovolt kV
kilowatt kW
kilowatt-hour kW-hr
kips per square inch ksi
to Contents
Appendix G
Unit Abbreviations
lines per inch lpi
lines per minute 1pm
lines per second lps
liter L
megabyte MB
megagram (metric ton) Mg
megahertz MHz
megajoule MJ
meter m
metric ton (tonne) t or Mg
mho per meter U/m
microsecond us
mile Spell out
miles per hour mph
milliamperes mA
millicurie mCi
millidarcy, millidarcies mD
milliequivalent meq
milligram mg
milliliter mL
millimeter mm
millimho mmho
million cubic feet (million = 10 6 ) MMcf
million cubic feet per day MMcf/D
million electron volts MeV
million standard cubic feet per day Use MMcf/D instead of MMscf/D
(see "standard cubic foot")
milliPascal mPa
millisecond ms
millisiemens mS
millivolt mV
mils per year mil/yr
minute min
mole mol
nanosecond ns
newton N
ohm ohm
ohm-centimeter ohm-cm
ohm-meter ohm-m
ounce oz
parts per million ppm
pascal Pa
picofarad pF
pint pt
porosity unit p.u.
pound (force) lbf
pound (mass) lbm
pound per cubic foot lbm/ft 3
pound per gallon lbm/gal
pounds of proppant added ppa
pounds per square inch psi
pounds per square inch absolute psia
pounds per square inch gauge psig
pounds per thousand barrels (salt content) ptb
quart qt
reservoir barrel res bbl
reservoir barrel per day RB/D
revolutions per minute rpm
saturation unit s.u.
second s
shots per foot spf
specific gravity sg
square sq
square centimeter cm 2
square foot ft 2
square inch in. 2
square meter m 2
square mile sq mile
square millimeter mm 2
standard std
standard cubic feet per day Use ft 3 /D instead of scf/D
(see "standard cubic foot")
standard cubic foot Use ft 3 or cf as specified on this list.
Do not use set unless the standard
conditions at which the measurement
was made are specified.
The straight volumetric conversion factor
is 1 ft 3 = 0.02831685 m 3
stock-tank barrel STB
stock-tank barrels per day STB/D
stoke St
teragram Tg
thousand cubic feet Mcf
thousand cubic feet per day Mcf/D
thousand pounds per square inch kpsi
thousand standard cubic feet per day Use Mcf/D instead of Mscf/D
(see "standard cubic foot")
tonne (metric ton) t
trillion cubic feet (trillion = 10 12 ) Tcf
trillion cubic feet per day Tcf/D
volt V
volume percent vol%
volume per volume vol/vol
watt W
weight percent wt%
yard yd
year (customary) yr
year (metric) a
Back to Contents
291
Appendix H
References
1. Overton HL and Lipson LB: "A Correlation of the Electrical
Properties of Drilling Fluids with Solids Content," Transactions,
AIME (1958) 213.
2. Desai KP and Moore EJ: "Equivalent NaCl Concentrations from
Ionic Concentrations," The Log Analyst (May-June 1969).
3. Gondouin M, Tixier MP, and Simard GL: "An Experimental Study
on the Influence of the Chemical Composition of Electrolytes on
the SP Curve," JPT (February 1957).
4. Segesman FF: "New SP Correction Charts," Geophysics
(December 1962) 27, No. 6, PI.
5. Alger RP, Locke S, Nagel WA, and Sherman H: "The Dual Spacing
Neutron Log-CNL," paper SPE 3565, presented at the 46th SPE
Annual Meeting, New Orleans, Louisiana, USA (1971).
6. Segesman FF and Liu OYH: "The Excavation Effect,"
Transactions of the SPWLA 12th Annual Logging Symposium
(1971).
7. Burke JA, Campbell RL Jr, and Schmidt AW: "The Litho-Porosity
Crossplot," Transactions of the SPWLA 10th Annual Logging
Symposium (1969), paper Y.
8. Clavier C and Rust DH: "MID-PLOT: A New Lithology
Technique," The Log Analyst (November-December 1976).
9. Tixier MP, Alger RP, Biggs WP, and Carpenter BN: "Dual
Induction-Laterolog: A New Tool for Resistivity Analysis," paper
713, presented at the 38th SPE Annual Meeting, New Orleans,
Louisiana, USA (1963).
10. Wahl JS, Nelligan WB, Frentrop AH, Johnstone CW, and
Schwartz RJ: "The Thermal Neutron Decay Time Log," SPE J
(December 1970).
11. Clavier C, Hoyle WR, and Meunier D: "Quantitative
Interpretation of Thermal Neutron Decay Time Logs, Part I and
II," JPT (June 1971).
12. Poupon A, Loy ME, and Tixier MP: "A Contribution to Electrical
Log Interpretation in Shaly Sands," JPT (June 1954).
13. Tixier MP, Alger RP, and Tanguy DR: "New Developments in
Induction and Sonic Logging," paper 1300G, presented at the
34th SPE Annual Meeting, Dallas, Texas, USA (1959).
14. Rodermund CG, Alger RP, and Tittman J: "Logging Empty
Holes," OGJ (June 1961).
15. Tixier MP: "Evaluation of Permeability from Electric Log
Resistivity Gradients," OGJ (June 1949).
16. Morris RL and Biggs WP: "Using Log-Derived Values of Water
Saturation and Porosity," Transactions of the SPWLA 8th
Annual Logging Symposium (1967).
17. Timur A: "An Investigation of Permeability, Porosity, and
Residual Water Saturation Relationships for Sandstone
Reservoirs," The Log Analyst (July-August 1968).
18. Wyllie MRJ, Gregory AR, and Gardner GHF: "Elastic Wave
Velocities in Heterogeneous and Porous Media," Geophysics
(January 1956) 21, No. 1.
19. Tixier MP, Alger RP, and Doh CA: "Sonic Logging," JPT (May
1959) 11, No. 5.
20. Raymer LL, Hunt ER, and Gardner JS: "An Improved Sonic
Transit Time-to-Porosity Transform," Transactions of the
SPWLA 21st Annual Logging Symposium (1980).
21. Coates GR and Dumanoir JR: "A New Approach to Improved
Log-Derived Permeability," The Log Analyst (January-February
1974).
22. Raymer LL: "Elevation and Hydrocarbon Density Correction for
Log-Derived Permeability Relationships," The Log Analyst
(May-June 1981).
23. Westaway P, Hertzog R, and Plasic RE: "The Gamma
Spectrometer Tool, Inelastic and Capture Gamma Ray
Spectroscopy for Reservoir Analysis," paper SPE 9461,
presented at the 55th SPE Annual Technical Conference
and Exhibition, Dallas, Texas, USA (1980).
24. Quirein JA, Gardner JS, and Watson JT: "Combined Natural
Gamma Ray Spectral/Litho-Density Measurements Applied to
Complex Lithologies," paper SPE 11143, presented at the 57th
SPE Annual Technical Conference and Exhibition, New Orleans,
Louisiana, USA (1982).
25. Harton RP, Hazen GA, Rau RN, and Best DL: "Electromagnetic
Propagation Logging: Advances in Technique and
Interpretation," paper SPE 9267, presented at the 55th SPE
Annual Technical Conference and Exhibition, Dallas, Texas,
USA (1980).
26. Serra 0, Baldwin JL, and Quirein JA: "Theory and Practical
Application of Natural Gamma Ray Spectrometry," Transactions
of the SPWLA 21st Annual Logging Symposium (1980).
27. Gardner JS and Dumanoir JL: "Litho-Density Log
Interpretation," Transactions of the SPWLA 21st Annual
Logging Symposium (1980).
28. Edmondson H and Raymer LL: "Radioactivity Logging
Parameters for Common Minerals," Transactions of the SPWLA
20th Annual Logging Symposium (1979).
29. Barber TD: "Real-Time Environmental Corrections for the
Phasor Dual Induction Tool," Transactions of the SPWLA 26th
Annual Logging Symposium (1985).
30. Roscoe BA and Grau J: "Response of the Carbon-Oxygen
Measurement for an Inelastic Gamma Ray Spectroscopy Tool,"
paper SPE 14460, presented at the 60th SPE Annual Technical
Conference and Exhibition, Las Vegas, Nevada, USA (1985).
292
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Appendix H
References
31. Freedman R and Grove G: "Interpretation of EPT-G Logs in the
Presence of Mudcakes," paper presented at the 63rd SPE
Annual Technical Conference and Exhibition, Houston, Texas,
USA (1988).
32. Gilchrist WA Jr, Galford JE, Flaum C, Soran PD, and Gardner JS:
"Improved Environmental Corrections for Compensated
Neutron Logs," paper SPE 15540, presented at the 61st SPE
Annual Technical Conference and Exhibition, New Orleans,
Louisiana, USA (1986).
33. Tabanou JR, Glowinski R, and Rouault GF: "SP Deconvolution
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of the SPWLA 28th Annual Logging Symposium (1987).
34. Kienitz C, Flaum C, Olesen J-R, and Barber T: "Accurate Logging
in Large Boreholes," Transactions of the SPWLA 27th Annual
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35. Galford JE, Flaum C, Gilchrist WA Jr, and Duckett SW:
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Technical Conference and Exhibition, New Orleans, Louisiana,
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Logging Symposium (1988).
38. Ellis DV, Flaum C, Galford JE, and Scott HD: "The Effect of
Formation Absorption on the Thermal Neutron Porosity
Measurement," paper presented at the 62nd SPE Annual
Technical Conference and Exhibition, Dallas, Texas, USA (1987).
39. Watfa M and Nurmi R: "Calculation of Saturation, Secondaiy
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Symposium (1987).
40. Brie A, Johnson DL, and Nurmi RD: "Effect of Spherical Pores
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49. Wyllie MRJ and Rose WD: "Some Theoretical Considerations
Related to the Quantitative Evaluation of the Physical
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JPT2 (1950), 189.
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293
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fJllTUDJ!
The Schlumberger "chartbook" was initially developed to
correct raw measurements to account for environmental
effects and to interpret the corrected measurements.
Although software may be more effective in deriving results,
especially in complex well situations, the chartbook still
serves two primary functions, for training and sensitivity
analysis.
Entering the chartbook will take you to the y,,,,,,.,.^
where you can access any chart by clicking its entrj
You can also browse the PDF normally.
Enterthe chartboo
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